<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers/mtd/ubi, branch v5.4.239</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>ubi: ubi_wl_put_peb: Fix infinite loop when wear-leveling work failed</title>
<updated>2023-03-11T15:44:10+00:00</updated>
<author>
<name>Zhihao Cheng</name>
<email>chengzhihao1@huawei.com</email>
</author>
<published>2022-06-13T06:59:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b5be23f6ae610bdb262160a1f294afee6d0e6a69'/>
<id>b5be23f6ae610bdb262160a1f294afee6d0e6a69</id>
<content type='text'>
[ Upstream commit 4d57a7333e26040f2b583983e1970d9d460e56b0 ]

Following process will trigger an infinite loop in ubi_wl_put_peb():

	ubifs_bgt		ubi_bgt
ubifs_leb_unmap
  ubi_leb_unmap
    ubi_eba_unmap_leb
      ubi_wl_put_peb	wear_leveling_worker
                          e1 = rb_entry(rb_first(&amp;ubi-&gt;used)
			  e2 = get_peb_for_wl(ubi)
			  ubi_io_read_vid_hdr  // return err (flash fault)
			  out_error:
			    ubi-&gt;move_from = ubi-&gt;move_to = NULL
			    wl_entry_destroy(ubi, e1)
			      ubi-&gt;lookuptbl[e-&gt;pnum] = NULL
      retry:
        e = ubi-&gt;lookuptbl[pnum];	// return NULL
	if (e == ubi-&gt;move_from) {	// NULL == NULL gets true
	  goto retry;			// infinite loop !!!

$ top
  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     COMMAND
  7676 root     20   0       0      0      0 R 100.0  0.0  ubifs_bgt0_0

Fix it by:
 1) Letting ubi_wl_put_peb() returns directly if wearl leveling entry has
    been removed from 'ubi-&gt;lookuptbl'.
 2) Using 'ubi-&gt;wl_lock' protecting wl entry deletion to preventing an
    use-after-free problem for wl entry in ubi_wl_put_peb().

Fetch a reproducer in [Link].

Fixes: 43f9b25a9cdd7b1 ("UBI: bugfix: protect from volume removal")
Fixes: ee59ba8b064f692 ("UBI: Fix stale pointers in ubi-&gt;lookuptbl")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216111
Signed-off-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 4d57a7333e26040f2b583983e1970d9d460e56b0 ]

Following process will trigger an infinite loop in ubi_wl_put_peb():

	ubifs_bgt		ubi_bgt
ubifs_leb_unmap
  ubi_leb_unmap
    ubi_eba_unmap_leb
      ubi_wl_put_peb	wear_leveling_worker
                          e1 = rb_entry(rb_first(&amp;ubi-&gt;used)
			  e2 = get_peb_for_wl(ubi)
			  ubi_io_read_vid_hdr  // return err (flash fault)
			  out_error:
			    ubi-&gt;move_from = ubi-&gt;move_to = NULL
			    wl_entry_destroy(ubi, e1)
			      ubi-&gt;lookuptbl[e-&gt;pnum] = NULL
      retry:
        e = ubi-&gt;lookuptbl[pnum];	// return NULL
	if (e == ubi-&gt;move_from) {	// NULL == NULL gets true
	  goto retry;			// infinite loop !!!

$ top
  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     COMMAND
  7676 root     20   0       0      0      0 R 100.0  0.0  ubifs_bgt0_0

Fix it by:
 1) Letting ubi_wl_put_peb() returns directly if wearl leveling entry has
    been removed from 'ubi-&gt;lookuptbl'.
 2) Using 'ubi-&gt;wl_lock' protecting wl entry deletion to preventing an
    use-after-free problem for wl entry in ubi_wl_put_peb().

Fetch a reproducer in [Link].

Fixes: 43f9b25a9cdd7b1 ("UBI: bugfix: protect from volume removal")
Fixes: ee59ba8b064f692 ("UBI: Fix stale pointers in ubi-&gt;lookuptbl")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216111
Signed-off-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ubi: Fix UAF wear-leveling entry in eraseblk_count_seq_show()</title>
<updated>2023-03-11T15:44:10+00:00</updated>
<author>
<name>Zhihao Cheng</name>
<email>chengzhihao1@huawei.com</email>
</author>
<published>2022-07-30T11:28:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=1cb14c06d6035539ef4215c4ba0871aea71d7c38'/>
<id>1cb14c06d6035539ef4215c4ba0871aea71d7c38</id>
<content type='text'>
[ Upstream commit a240bc5c43130c6aa50831d7caaa02a1d84e1bce ]

Wear-leveling entry could be freed in error path, which may be accessed
again in eraseblk_count_seq_show(), for example:

__erase_worker                eraseblk_count_seq_show
                                wl = ubi-&gt;lookuptbl[*block_number]
				if (wl)
  wl_entry_destroy
    ubi-&gt;lookuptbl[e-&gt;pnum] = NULL
    kmem_cache_free(ubi_wl_entry_slab, e)
		                   erase_count = wl-&gt;ec  // UAF!

Wear-leveling entry updating/accessing in ubi-&gt;lookuptbl should be
protected by ubi-&gt;wl_lock, fix it by adding ubi-&gt;wl_lock to serialize
wl entry accessing between wl_entry_destroy() and
eraseblk_count_seq_show().

Fetch a reproducer in [Link].

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216305
Fixes: 7bccd12d27b7e3 ("ubi: Add debugfs file for tracking PEB state")
Fixes: 801c135ce73d5d ("UBI: Unsorted Block Images")
Signed-off-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit a240bc5c43130c6aa50831d7caaa02a1d84e1bce ]

Wear-leveling entry could be freed in error path, which may be accessed
again in eraseblk_count_seq_show(), for example:

__erase_worker                eraseblk_count_seq_show
                                wl = ubi-&gt;lookuptbl[*block_number]
				if (wl)
  wl_entry_destroy
    ubi-&gt;lookuptbl[e-&gt;pnum] = NULL
    kmem_cache_free(ubi_wl_entry_slab, e)
		                   erase_count = wl-&gt;ec  // UAF!

Wear-leveling entry updating/accessing in ubi-&gt;lookuptbl should be
protected by ubi-&gt;wl_lock, fix it by adding ubi-&gt;wl_lock to serialize
wl entry accessing between wl_entry_destroy() and
eraseblk_count_seq_show().

Fetch a reproducer in [Link].

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216305
Fixes: 7bccd12d27b7e3 ("ubi: Add debugfs file for tracking PEB state")
Fixes: 801c135ce73d5d ("UBI: Unsorted Block Images")
Signed-off-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ubi: Fix possible null-ptr-deref in ubi_free_volume()</title>
<updated>2023-03-11T15:44:10+00:00</updated>
<author>
<name>Yang Yingliang</name>
<email>yangyingliang@huawei.com</email>
</author>
<published>2022-11-14T10:26:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=234c53e57424992e657e6f4acc00d3df0983176f'/>
<id>234c53e57424992e657e6f4acc00d3df0983176f</id>
<content type='text'>
[ Upstream commit c15859bfd326c10230f09cb48a17f8a35f190342 ]

It willl cause null-ptr-deref in the following case:

uif_init()
  ubi_add_volume()
    cdev_add() -&gt; if it fails, call kill_volumes()
    device_register()

kill_volumes() -&gt; if ubi_add_volume() fails call this function
  ubi_free_volume()
    cdev_del()
    device_unregister() -&gt; trying to delete a not added device,
			   it causes null-ptr-deref

So in ubi_free_volume(), it delete devices whether they are added
or not, it will causes null-ptr-deref.

Handle the error case whlie calling ubi_add_volume() to fix this
problem. If add volume fails, set the corresponding vol to null,
so it can not be accessed in kill_volumes() and release the
resource in ubi_add_volume() error path.

Fixes: 801c135ce73d ("UBI: Unsorted Block Images")
Suggested-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Yang Yingliang &lt;yangyingliang@huawei.com&gt;
Reviewed-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit c15859bfd326c10230f09cb48a17f8a35f190342 ]

It willl cause null-ptr-deref in the following case:

uif_init()
  ubi_add_volume()
    cdev_add() -&gt; if it fails, call kill_volumes()
    device_register()

kill_volumes() -&gt; if ubi_add_volume() fails call this function
  ubi_free_volume()
    cdev_del()
    device_unregister() -&gt; trying to delete a not added device,
			   it causes null-ptr-deref

So in ubi_free_volume(), it delete devices whether they are added
or not, it will causes null-ptr-deref.

Handle the error case whlie calling ubi_add_volume() to fix this
problem. If add volume fails, set the corresponding vol to null,
so it can not be accessed in kill_volumes() and release the
resource in ubi_add_volume() error path.

Fixes: 801c135ce73d ("UBI: Unsorted Block Images")
Suggested-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Yang Yingliang &lt;yangyingliang@huawei.com&gt;
Reviewed-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ubi: Fix unreferenced object reported by kmemleak in ubi_resize_volume()</title>
<updated>2023-03-11T15:44:09+00:00</updated>
<author>
<name>Li Zetao</name>
<email>lizetao1@huawei.com</email>
</author>
<published>2022-10-21T10:21:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=07b60f7452d2fa731737552937cb81821919f874'/>
<id>07b60f7452d2fa731737552937cb81821919f874</id>
<content type='text'>
[ Upstream commit 1e591ea072df7211f64542a09482b5f81cb3ad27 ]

There is a memory leaks problem reported by kmemleak:

unreferenced object 0xffff888102007a00 (size 128):
  comm "ubirsvol", pid 32090, jiffies 4298464136 (age 2361.231s)
  hex dump (first 32 bytes):
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
  backtrace:
[&lt;ffffffff8176cecd&gt;] __kmalloc+0x4d/0x150
[&lt;ffffffffa02a9a36&gt;] ubi_eba_create_table+0x76/0x170 [ubi]
[&lt;ffffffffa029764e&gt;] ubi_resize_volume+0x1be/0xbc0 [ubi]
[&lt;ffffffffa02a3321&gt;] ubi_cdev_ioctl+0x701/0x1850 [ubi]
[&lt;ffffffff81975d2d&gt;] __x64_sys_ioctl+0x11d/0x170
[&lt;ffffffff83c142a5&gt;] do_syscall_64+0x35/0x80
[&lt;ffffffff83e0006a&gt;] entry_SYSCALL_64_after_hwframe+0x46/0xb0

This is due to a mismatch between create and destroy interfaces, and
in detail that "new_eba_tbl" created by ubi_eba_create_table() but
destroyed by kfree(), while will causing "new_eba_tbl-&gt;entries" not
freed.

Fix it by replacing kfree(new_eba_tbl) with
ubi_eba_destroy_table(new_eba_tbl)

Fixes: 799dca34ac54 ("UBI: hide EBA internals")
Signed-off-by: Li Zetao &lt;lizetao1@huawei.com&gt;
Reviewed-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 1e591ea072df7211f64542a09482b5f81cb3ad27 ]

There is a memory leaks problem reported by kmemleak:

unreferenced object 0xffff888102007a00 (size 128):
  comm "ubirsvol", pid 32090, jiffies 4298464136 (age 2361.231s)
  hex dump (first 32 bytes):
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
  backtrace:
[&lt;ffffffff8176cecd&gt;] __kmalloc+0x4d/0x150
[&lt;ffffffffa02a9a36&gt;] ubi_eba_create_table+0x76/0x170 [ubi]
[&lt;ffffffffa029764e&gt;] ubi_resize_volume+0x1be/0xbc0 [ubi]
[&lt;ffffffffa02a3321&gt;] ubi_cdev_ioctl+0x701/0x1850 [ubi]
[&lt;ffffffff81975d2d&gt;] __x64_sys_ioctl+0x11d/0x170
[&lt;ffffffff83c142a5&gt;] do_syscall_64+0x35/0x80
[&lt;ffffffff83e0006a&gt;] entry_SYSCALL_64_after_hwframe+0x46/0xb0

This is due to a mismatch between create and destroy interfaces, and
in detail that "new_eba_tbl" created by ubi_eba_create_table() but
destroyed by kfree(), while will causing "new_eba_tbl-&gt;entries" not
freed.

Fix it by replacing kfree(new_eba_tbl) with
ubi_eba_destroy_table(new_eba_tbl)

Fixes: 799dca34ac54 ("UBI: hide EBA internals")
Signed-off-by: Li Zetao &lt;lizetao1@huawei.com&gt;
Reviewed-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ubi: Fix use-after-free when volume resizing failed</title>
<updated>2023-03-11T15:44:09+00:00</updated>
<author>
<name>Li Zetao</name>
<email>lizetao1@huawei.com</email>
</author>
<published>2022-10-21T10:21:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9c8be1f165baee53b5a36ea0b3c9281d403a1d0b'/>
<id>9c8be1f165baee53b5a36ea0b3c9281d403a1d0b</id>
<content type='text'>
[ Upstream commit 9af31d6ec1a4be4caab2550096c6bd2ba8fba472 ]

There is an use-after-free problem reported by KASAN:
  ==================================================================
  BUG: KASAN: use-after-free in ubi_eba_copy_table+0x11f/0x1c0 [ubi]
  Read of size 8 at addr ffff888101eec008 by task ubirsvol/4735

  CPU: 2 PID: 4735 Comm: ubirsvol
  Not tainted 6.1.0-rc1-00003-g84fa3304a7fc-dirty #14
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
  BIOS 1.14.0-1.fc33 04/01/2014
  Call Trace:
   &lt;TASK&gt;
   dump_stack_lvl+0x34/0x44
   print_report+0x171/0x472
   kasan_report+0xad/0x130
   ubi_eba_copy_table+0x11f/0x1c0 [ubi]
   ubi_resize_volume+0x4f9/0xbc0 [ubi]
   ubi_cdev_ioctl+0x701/0x1850 [ubi]
   __x64_sys_ioctl+0x11d/0x170
   do_syscall_64+0x35/0x80
   entry_SYSCALL_64_after_hwframe+0x46/0xb0
   &lt;/TASK&gt;

When ubi_change_vtbl_record() returns an error in ubi_resize_volume(),
"new_eba_tbl" will be freed on error handing path, but it is holded
by "vol-&gt;eba_tbl" in ubi_eba_replace_table(). It means that the liftcycle
of "vol-&gt;eba_tbl" and "vol" are different, so when resizing volume in
next time, it causing an use-after-free fault.

Fix it by not freeing "new_eba_tbl" after it replaced in
ubi_eba_replace_table(), while will be freed in next volume resizing.

Fixes: 801c135ce73d ("UBI: Unsorted Block Images")
Signed-off-by: Li Zetao &lt;lizetao1@huawei.com&gt;
Reviewed-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 9af31d6ec1a4be4caab2550096c6bd2ba8fba472 ]

There is an use-after-free problem reported by KASAN:
  ==================================================================
  BUG: KASAN: use-after-free in ubi_eba_copy_table+0x11f/0x1c0 [ubi]
  Read of size 8 at addr ffff888101eec008 by task ubirsvol/4735

  CPU: 2 PID: 4735 Comm: ubirsvol
  Not tainted 6.1.0-rc1-00003-g84fa3304a7fc-dirty #14
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
  BIOS 1.14.0-1.fc33 04/01/2014
  Call Trace:
   &lt;TASK&gt;
   dump_stack_lvl+0x34/0x44
   print_report+0x171/0x472
   kasan_report+0xad/0x130
   ubi_eba_copy_table+0x11f/0x1c0 [ubi]
   ubi_resize_volume+0x4f9/0xbc0 [ubi]
   ubi_cdev_ioctl+0x701/0x1850 [ubi]
   __x64_sys_ioctl+0x11d/0x170
   do_syscall_64+0x35/0x80
   entry_SYSCALL_64_after_hwframe+0x46/0xb0
   &lt;/TASK&gt;

When ubi_change_vtbl_record() returns an error in ubi_resize_volume(),
"new_eba_tbl" will be freed on error handing path, but it is holded
by "vol-&gt;eba_tbl" in ubi_eba_replace_table(). It means that the liftcycle
of "vol-&gt;eba_tbl" and "vol" are different, so when resizing volume in
next time, it causing an use-after-free fault.

Fix it by not freeing "new_eba_tbl" after it replaced in
ubi_eba_replace_table(), while will be freed in next volume resizing.

Fixes: 801c135ce73d ("UBI: Unsorted Block Images")
Signed-off-by: Li Zetao &lt;lizetao1@huawei.com&gt;
Reviewed-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ubi: ensure that VID header offset + VID header size &lt;= alloc, size</title>
<updated>2023-03-11T15:44:08+00:00</updated>
<author>
<name>George Kennedy</name>
<email>george.kennedy@oracle.com</email>
</author>
<published>2022-11-15T15:14:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f7adb740f97b6fa84e658892dcb08e37a31a4e77'/>
<id>f7adb740f97b6fa84e658892dcb08e37a31a4e77</id>
<content type='text'>
[ Upstream commit 1b42b1a36fc946f0d7088425b90d491b4257ca3e ]

Ensure that the VID header offset + VID header size does not exceed
the allocated area to avoid slab OOB.

BUG: KASAN: slab-out-of-bounds in crc32_body lib/crc32.c:111 [inline]
BUG: KASAN: slab-out-of-bounds in crc32_le_generic lib/crc32.c:179 [inline]
BUG: KASAN: slab-out-of-bounds in crc32_le_base+0x58c/0x626 lib/crc32.c:197
Read of size 4 at addr ffff88802bb36f00 by task syz-executor136/1555

CPU: 2 PID: 1555 Comm: syz-executor136 Tainted: G        W
6.0.0-1868 #1
Hardware name: Red Hat KVM, BIOS 1.13.0-2.module+el8.3.0+7860+a7792d29
04/01/2014
Call Trace:
  &lt;TASK&gt;
  __dump_stack lib/dump_stack.c:88 [inline]
  dump_stack_lvl+0x85/0xad lib/dump_stack.c:106
  print_address_description mm/kasan/report.c:317 [inline]
  print_report.cold.13+0xb6/0x6bb mm/kasan/report.c:433
  kasan_report+0xa7/0x11b mm/kasan/report.c:495
  crc32_body lib/crc32.c:111 [inline]
  crc32_le_generic lib/crc32.c:179 [inline]
  crc32_le_base+0x58c/0x626 lib/crc32.c:197
  ubi_io_write_vid_hdr+0x1b7/0x472 drivers/mtd/ubi/io.c:1067
  create_vtbl+0x4d5/0x9c4 drivers/mtd/ubi/vtbl.c:317
  create_empty_lvol drivers/mtd/ubi/vtbl.c:500 [inline]
  ubi_read_volume_table+0x67b/0x288a drivers/mtd/ubi/vtbl.c:812
  ubi_attach+0xf34/0x1603 drivers/mtd/ubi/attach.c:1601
  ubi_attach_mtd_dev+0x6f3/0x185e drivers/mtd/ubi/build.c:965
  ctrl_cdev_ioctl+0x2db/0x347 drivers/mtd/ubi/cdev.c:1043
  vfs_ioctl fs/ioctl.c:51 [inline]
  __do_sys_ioctl fs/ioctl.c:870 [inline]
  __se_sys_ioctl fs/ioctl.c:856 [inline]
  __x64_sys_ioctl+0x193/0x213 fs/ioctl.c:856
  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
  do_syscall_64+0x3e/0x86 arch/x86/entry/common.c:80
  entry_SYSCALL_64_after_hwframe+0x63/0x0
RIP: 0033:0x7f96d5cf753d
Code:
RSP: 002b:00007fffd72206f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f96d5cf753d
RDX: 0000000020000080 RSI: 0000000040186f40 RDI: 0000000000000003
RBP: 0000000000400cd0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000400be0
R13: 00007fffd72207e0 R14: 0000000000000000 R15: 0000000000000000
  &lt;/TASK&gt;

Allocated by task 1555:
  kasan_save_stack+0x20/0x3d mm/kasan/common.c:38
  kasan_set_track mm/kasan/common.c:45 [inline]
  set_alloc_info mm/kasan/common.c:437 [inline]
  ____kasan_kmalloc mm/kasan/common.c:516 [inline]
  __kasan_kmalloc+0x88/0xa3 mm/kasan/common.c:525
  kasan_kmalloc include/linux/kasan.h:234 [inline]
  __kmalloc+0x138/0x257 mm/slub.c:4429
  kmalloc include/linux/slab.h:605 [inline]
  ubi_alloc_vid_buf drivers/mtd/ubi/ubi.h:1093 [inline]
  create_vtbl+0xcc/0x9c4 drivers/mtd/ubi/vtbl.c:295
  create_empty_lvol drivers/mtd/ubi/vtbl.c:500 [inline]
  ubi_read_volume_table+0x67b/0x288a drivers/mtd/ubi/vtbl.c:812
  ubi_attach+0xf34/0x1603 drivers/mtd/ubi/attach.c:1601
  ubi_attach_mtd_dev+0x6f3/0x185e drivers/mtd/ubi/build.c:965
  ctrl_cdev_ioctl+0x2db/0x347 drivers/mtd/ubi/cdev.c:1043
  vfs_ioctl fs/ioctl.c:51 [inline]
  __do_sys_ioctl fs/ioctl.c:870 [inline]
  __se_sys_ioctl fs/ioctl.c:856 [inline]
  __x64_sys_ioctl+0x193/0x213 fs/ioctl.c:856
  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
  do_syscall_64+0x3e/0x86 arch/x86/entry/common.c:80
  entry_SYSCALL_64_after_hwframe+0x63/0x0

The buggy address belongs to the object at ffff88802bb36e00
  which belongs to the cache kmalloc-256 of size 256
The buggy address is located 0 bytes to the right of
  256-byte region [ffff88802bb36e00, ffff88802bb36f00)

The buggy address belongs to the physical page:
page:00000000ea4d1263 refcount:1 mapcount:0 mapping:0000000000000000
index:0x0 pfn:0x2bb36
head:00000000ea4d1263 order:1 compound_mapcount:0 compound_pincount:0
flags: 0xfffffc0010200(slab|head|node=0|zone=1|lastcpupid=0x1fffff)
raw: 000fffffc0010200 ffffea000066c300 dead000000000003 ffff888100042b40
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff88802bb36e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  ffff88802bb36e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
&gt;ffff88802bb36f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                    ^
  ffff88802bb36f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff88802bb37000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Fixes: 801c135ce73d ("UBI: Unsorted Block Images")
Reported-by: syzkaller &lt;syzkaller@googlegroups.com&gt;
Signed-off-by: George Kennedy &lt;george.kennedy@oracle.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 1b42b1a36fc946f0d7088425b90d491b4257ca3e ]

Ensure that the VID header offset + VID header size does not exceed
the allocated area to avoid slab OOB.

BUG: KASAN: slab-out-of-bounds in crc32_body lib/crc32.c:111 [inline]
BUG: KASAN: slab-out-of-bounds in crc32_le_generic lib/crc32.c:179 [inline]
BUG: KASAN: slab-out-of-bounds in crc32_le_base+0x58c/0x626 lib/crc32.c:197
Read of size 4 at addr ffff88802bb36f00 by task syz-executor136/1555

CPU: 2 PID: 1555 Comm: syz-executor136 Tainted: G        W
6.0.0-1868 #1
Hardware name: Red Hat KVM, BIOS 1.13.0-2.module+el8.3.0+7860+a7792d29
04/01/2014
Call Trace:
  &lt;TASK&gt;
  __dump_stack lib/dump_stack.c:88 [inline]
  dump_stack_lvl+0x85/0xad lib/dump_stack.c:106
  print_address_description mm/kasan/report.c:317 [inline]
  print_report.cold.13+0xb6/0x6bb mm/kasan/report.c:433
  kasan_report+0xa7/0x11b mm/kasan/report.c:495
  crc32_body lib/crc32.c:111 [inline]
  crc32_le_generic lib/crc32.c:179 [inline]
  crc32_le_base+0x58c/0x626 lib/crc32.c:197
  ubi_io_write_vid_hdr+0x1b7/0x472 drivers/mtd/ubi/io.c:1067
  create_vtbl+0x4d5/0x9c4 drivers/mtd/ubi/vtbl.c:317
  create_empty_lvol drivers/mtd/ubi/vtbl.c:500 [inline]
  ubi_read_volume_table+0x67b/0x288a drivers/mtd/ubi/vtbl.c:812
  ubi_attach+0xf34/0x1603 drivers/mtd/ubi/attach.c:1601
  ubi_attach_mtd_dev+0x6f3/0x185e drivers/mtd/ubi/build.c:965
  ctrl_cdev_ioctl+0x2db/0x347 drivers/mtd/ubi/cdev.c:1043
  vfs_ioctl fs/ioctl.c:51 [inline]
  __do_sys_ioctl fs/ioctl.c:870 [inline]
  __se_sys_ioctl fs/ioctl.c:856 [inline]
  __x64_sys_ioctl+0x193/0x213 fs/ioctl.c:856
  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
  do_syscall_64+0x3e/0x86 arch/x86/entry/common.c:80
  entry_SYSCALL_64_after_hwframe+0x63/0x0
RIP: 0033:0x7f96d5cf753d
Code:
RSP: 002b:00007fffd72206f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f96d5cf753d
RDX: 0000000020000080 RSI: 0000000040186f40 RDI: 0000000000000003
RBP: 0000000000400cd0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000400be0
R13: 00007fffd72207e0 R14: 0000000000000000 R15: 0000000000000000
  &lt;/TASK&gt;

Allocated by task 1555:
  kasan_save_stack+0x20/0x3d mm/kasan/common.c:38
  kasan_set_track mm/kasan/common.c:45 [inline]
  set_alloc_info mm/kasan/common.c:437 [inline]
  ____kasan_kmalloc mm/kasan/common.c:516 [inline]
  __kasan_kmalloc+0x88/0xa3 mm/kasan/common.c:525
  kasan_kmalloc include/linux/kasan.h:234 [inline]
  __kmalloc+0x138/0x257 mm/slub.c:4429
  kmalloc include/linux/slab.h:605 [inline]
  ubi_alloc_vid_buf drivers/mtd/ubi/ubi.h:1093 [inline]
  create_vtbl+0xcc/0x9c4 drivers/mtd/ubi/vtbl.c:295
  create_empty_lvol drivers/mtd/ubi/vtbl.c:500 [inline]
  ubi_read_volume_table+0x67b/0x288a drivers/mtd/ubi/vtbl.c:812
  ubi_attach+0xf34/0x1603 drivers/mtd/ubi/attach.c:1601
  ubi_attach_mtd_dev+0x6f3/0x185e drivers/mtd/ubi/build.c:965
  ctrl_cdev_ioctl+0x2db/0x347 drivers/mtd/ubi/cdev.c:1043
  vfs_ioctl fs/ioctl.c:51 [inline]
  __do_sys_ioctl fs/ioctl.c:870 [inline]
  __se_sys_ioctl fs/ioctl.c:856 [inline]
  __x64_sys_ioctl+0x193/0x213 fs/ioctl.c:856
  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
  do_syscall_64+0x3e/0x86 arch/x86/entry/common.c:80
  entry_SYSCALL_64_after_hwframe+0x63/0x0

The buggy address belongs to the object at ffff88802bb36e00
  which belongs to the cache kmalloc-256 of size 256
The buggy address is located 0 bytes to the right of
  256-byte region [ffff88802bb36e00, ffff88802bb36f00)

The buggy address belongs to the physical page:
page:00000000ea4d1263 refcount:1 mapcount:0 mapping:0000000000000000
index:0x0 pfn:0x2bb36
head:00000000ea4d1263 order:1 compound_mapcount:0 compound_pincount:0
flags: 0xfffffc0010200(slab|head|node=0|zone=1|lastcpupid=0x1fffff)
raw: 000fffffc0010200 ffffea000066c300 dead000000000003 ffff888100042b40
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff88802bb36e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  ffff88802bb36e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
&gt;ffff88802bb36f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                    ^
  ffff88802bb36f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff88802bb37000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Fixes: 801c135ce73d ("UBI: Unsorted Block Images")
Reported-by: syzkaller &lt;syzkaller@googlegroups.com&gt;
Signed-off-by: George Kennedy &lt;george.kennedy@oracle.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ubi: ubi_create_volume: Fix use-after-free when volume creation failed</title>
<updated>2022-06-14T16:11:55+00:00</updated>
<author>
<name>Zhihao Cheng</name>
<email>chengzhihao1@huawei.com</email>
</author>
<published>2022-05-10T12:31:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=8302620aeb940f386817321d272b12411ae7d39f'/>
<id>8302620aeb940f386817321d272b12411ae7d39f</id>
<content type='text'>
[ Upstream commit 8c03a1c21d72210f81cb369cc528e3fde4b45411 ]

There is an use-after-free problem for 'eba_tbl' in ubi_create_volume()'s
error handling path:

  ubi_eba_replace_table(vol, eba_tbl)
    vol-&gt;eba_tbl = tbl
out_mapping:
  ubi_eba_destroy_table(eba_tbl)   // Free 'eba_tbl'
out_unlock:
  put_device(&amp;vol-&gt;dev)
    vol_release
      kfree(tbl-&gt;entries)	  // UAF

Fix it by removing redundant 'eba_tbl' releasing.
Fetch a reproducer in [Link].

Fixes: 493cfaeaa0c9b ("mtd: utilize new cdev_device_add helper function")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215965
Signed-off-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 8c03a1c21d72210f81cb369cc528e3fde4b45411 ]

There is an use-after-free problem for 'eba_tbl' in ubi_create_volume()'s
error handling path:

  ubi_eba_replace_table(vol, eba_tbl)
    vol-&gt;eba_tbl = tbl
out_mapping:
  ubi_eba_destroy_table(eba_tbl)   // Free 'eba_tbl'
out_unlock:
  put_device(&amp;vol-&gt;dev)
    vol_release
      kfree(tbl-&gt;entries)	  // UAF

Fix it by removing redundant 'eba_tbl' releasing.
Fetch a reproducer in [Link].

Fixes: 493cfaeaa0c9b ("mtd: utilize new cdev_device_add helper function")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215965
Signed-off-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ubi: fastmap: Return error code if memory allocation fails in add_aeb()</title>
<updated>2022-04-15T12:18:30+00:00</updated>
<author>
<name>Zhihao Cheng</name>
<email>chengzhihao1@huawei.com</email>
</author>
<published>2021-12-27T03:22:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=32a76a5574949a190a0fc32afa9bba0f08771109'/>
<id>32a76a5574949a190a0fc32afa9bba0f08771109</id>
<content type='text'>
commit c3c07fc25f37c157fde041b3a0c3dfcb1590cbce upstream.

Abort fastmap scanning and return error code if memory allocation fails
in add_aeb(). Otherwise ubi will get wrong peb statistics information
after scanning.

Fixes: dbb7d2a88d2a7b ("UBI: Add fastmap core")
Signed-off-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit c3c07fc25f37c157fde041b3a0c3dfcb1590cbce upstream.

Abort fastmap scanning and return error code if memory allocation fails
in add_aeb(). Otherwise ubi will get wrong peb statistics information
after scanning.

Fixes: dbb7d2a88d2a7b ("UBI: Add fastmap core")
Signed-off-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ubi: Fix race condition between ctrl_cdev_ioctl and ubi_cdev_ioctl</title>
<updated>2022-04-15T12:18:29+00:00</updated>
<author>
<name>Baokun Li</name>
<email>libaokun1@huawei.com</email>
</author>
<published>2021-11-05T09:30:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d727fd32cbd1abf3465f607021bc9c746f17b5a8'/>
<id>d727fd32cbd1abf3465f607021bc9c746f17b5a8</id>
<content type='text'>
commit 3cbf0e392f173ba0ce425968c8374a6aa3e90f2e upstream.

Hulk Robot reported a KASAN report about use-after-free:
 ==================================================================
 BUG: KASAN: use-after-free in __list_del_entry_valid+0x13d/0x160
 Read of size 8 at addr ffff888035e37d98 by task ubiattach/1385
 [...]
 Call Trace:
  klist_dec_and_del+0xa7/0x4a0
  klist_put+0xc7/0x1a0
  device_del+0x4d4/0xed0
  cdev_device_del+0x1a/0x80
  ubi_attach_mtd_dev+0x2951/0x34b0 [ubi]
  ctrl_cdev_ioctl+0x286/0x2f0 [ubi]

 Allocated by task 1414:
  device_add+0x60a/0x18b0
  cdev_device_add+0x103/0x170
  ubi_create_volume+0x1118/0x1a10 [ubi]
  ubi_cdev_ioctl+0xb7f/0x1ba0 [ubi]

 Freed by task 1385:
  cdev_device_del+0x1a/0x80
  ubi_remove_volume+0x438/0x6c0 [ubi]
  ubi_cdev_ioctl+0xbf4/0x1ba0 [ubi]
 [...]
 ==================================================================

The lock held by ctrl_cdev_ioctl is ubi_devices_mutex, but the lock held
by ubi_cdev_ioctl is ubi-&gt;device_mutex. Therefore, the two locks can be
concurrent.

ctrl_cdev_ioctl contains two operations: ubi_attach and ubi_detach.
ubi_detach is bug-free because it uses reference counting to prevent
concurrency. However, uif_init and uif_close in ubi_attach may race with
ubi_cdev_ioctl.

uif_init will race with ubi_cdev_ioctl as in the following stack.
           cpu1                   cpu2                  cpu3
_______________________|________________________|______________________
ctrl_cdev_ioctl
 ubi_attach_mtd_dev
  uif_init
                           ubi_cdev_ioctl
                            ubi_create_volume
                             cdev_device_add
   ubi_add_volume
   // sysfs exist
   kill_volumes
                                                    ubi_cdev_ioctl
                                                     ubi_remove_volume
                                                      cdev_device_del
                                                       // first free
    ubi_free_volume
     cdev_del
     // double free
   cdev_device_del

And uif_close will race with ubi_cdev_ioctl as in the following stack.
           cpu1                   cpu2                  cpu3
_______________________|________________________|______________________
ctrl_cdev_ioctl
 ubi_attach_mtd_dev
  uif_init
                           ubi_cdev_ioctl
                            ubi_create_volume
                             cdev_device_add
  ubi_debugfs_init_dev
  //error goto out_uif;
  uif_close
   kill_volumes
                                                    ubi_cdev_ioctl
                                                     ubi_remove_volume
                                                      cdev_device_del
                                                       // first free
    ubi_free_volume
    // double free

The cause of this problem is that commit 714fb87e8bc0 make device
"available" before it becomes accessible via sysfs. Therefore, we
roll back the modification. We will fix the race condition between
ubi device creation and udev by removing ubi_get_device in
vol_attribute_show and dev_attribute_show.This avoids accessing
uninitialized ubi_devices[ubi_num].

ubi_get_device is used to prevent devices from being deleted during
sysfs execution. However, now kernfs ensures that devices will not
be deleted before all reference counting are released.
The key process is shown in the following stack.

device_del
  device_remove_attrs
    device_remove_groups
      sysfs_remove_groups
        sysfs_remove_group
          remove_files
            kernfs_remove_by_name
              kernfs_remove_by_name_ns
                __kernfs_remove
                  kernfs_drain

Fixes: 714fb87e8bc0 ("ubi: Fix race condition between ubi device creation and udev")
Reported-by: Hulk Robot &lt;hulkci@huawei.com&gt;
Signed-off-by: Baokun Li &lt;libaokun1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 3cbf0e392f173ba0ce425968c8374a6aa3e90f2e upstream.

Hulk Robot reported a KASAN report about use-after-free:
 ==================================================================
 BUG: KASAN: use-after-free in __list_del_entry_valid+0x13d/0x160
 Read of size 8 at addr ffff888035e37d98 by task ubiattach/1385
 [...]
 Call Trace:
  klist_dec_and_del+0xa7/0x4a0
  klist_put+0xc7/0x1a0
  device_del+0x4d4/0xed0
  cdev_device_del+0x1a/0x80
  ubi_attach_mtd_dev+0x2951/0x34b0 [ubi]
  ctrl_cdev_ioctl+0x286/0x2f0 [ubi]

 Allocated by task 1414:
  device_add+0x60a/0x18b0
  cdev_device_add+0x103/0x170
  ubi_create_volume+0x1118/0x1a10 [ubi]
  ubi_cdev_ioctl+0xb7f/0x1ba0 [ubi]

 Freed by task 1385:
  cdev_device_del+0x1a/0x80
  ubi_remove_volume+0x438/0x6c0 [ubi]
  ubi_cdev_ioctl+0xbf4/0x1ba0 [ubi]
 [...]
 ==================================================================

The lock held by ctrl_cdev_ioctl is ubi_devices_mutex, but the lock held
by ubi_cdev_ioctl is ubi-&gt;device_mutex. Therefore, the two locks can be
concurrent.

ctrl_cdev_ioctl contains two operations: ubi_attach and ubi_detach.
ubi_detach is bug-free because it uses reference counting to prevent
concurrency. However, uif_init and uif_close in ubi_attach may race with
ubi_cdev_ioctl.

uif_init will race with ubi_cdev_ioctl as in the following stack.
           cpu1                   cpu2                  cpu3
_______________________|________________________|______________________
ctrl_cdev_ioctl
 ubi_attach_mtd_dev
  uif_init
                           ubi_cdev_ioctl
                            ubi_create_volume
                             cdev_device_add
   ubi_add_volume
   // sysfs exist
   kill_volumes
                                                    ubi_cdev_ioctl
                                                     ubi_remove_volume
                                                      cdev_device_del
                                                       // first free
    ubi_free_volume
     cdev_del
     // double free
   cdev_device_del

And uif_close will race with ubi_cdev_ioctl as in the following stack.
           cpu1                   cpu2                  cpu3
_______________________|________________________|______________________
ctrl_cdev_ioctl
 ubi_attach_mtd_dev
  uif_init
                           ubi_cdev_ioctl
                            ubi_create_volume
                             cdev_device_add
  ubi_debugfs_init_dev
  //error goto out_uif;
  uif_close
   kill_volumes
                                                    ubi_cdev_ioctl
                                                     ubi_remove_volume
                                                      cdev_device_del
                                                       // first free
    ubi_free_volume
    // double free

The cause of this problem is that commit 714fb87e8bc0 make device
"available" before it becomes accessible via sysfs. Therefore, we
roll back the modification. We will fix the race condition between
ubi device creation and udev by removing ubi_get_device in
vol_attribute_show and dev_attribute_show.This avoids accessing
uninitialized ubi_devices[ubi_num].

ubi_get_device is used to prevent devices from being deleted during
sysfs execution. However, now kernfs ensures that devices will not
be deleted before all reference counting are released.
The key process is shown in the following stack.

device_del
  device_remove_attrs
    device_remove_groups
      sysfs_remove_groups
        sysfs_remove_group
          remove_files
            kernfs_remove_by_name
              kernfs_remove_by_name_ns
                __kernfs_remove
                  kernfs_drain

Fixes: 714fb87e8bc0 ("ubi: Fix race condition between ubi device creation and udev")
Reported-by: Hulk Robot &lt;hulkci@huawei.com&gt;
Signed-off-by: Baokun Li &lt;libaokun1@huawei.com&gt;
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ubi: check kthread_should_stop() after the setting of task state</title>
<updated>2020-11-05T10:43:33+00:00</updated>
<author>
<name>Zhihao Cheng</name>
<email>chengzhihao1@huawei.com</email>
</author>
<published>2020-06-01T09:12:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=da3bb6fa23f1a4a2f0efa625621106d1d3e5892c'/>
<id>da3bb6fa23f1a4a2f0efa625621106d1d3e5892c</id>
<content type='text'>
commit d005f8c6588efcfbe88099b6edafc6f58c84a9c1 upstream.

A detach hung is possible when a race occurs between the detach process
and the ubi background thread. The following sequences outline the race:

  ubi thread: if (list_empty(&amp;ubi-&gt;works)...

  ubi detach: set_bit(KTHREAD_SHOULD_STOP, &amp;kthread-&gt;flags)
              =&gt; by kthread_stop()
              wake_up_process()
              =&gt; ubi thread is still running, so 0 is returned

  ubi thread: set_current_state(TASK_INTERRUPTIBLE)
              schedule()
              =&gt; ubi thread will never be scheduled again

  ubi detach: wait_for_completion()
              =&gt; hung task!

To fix that, we need to check kthread_should_stop() after we set the
task state, so the ubi thread will either see the stop bit and exit or
the task state is reset to runnable such that it isn't scheduled out
indefinitely.

Signed-off-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Fixes: 801c135ce73d5df1ca ("UBI: Unsorted Block Images")
Reported-by: syzbot+853639d0cb16c31c7a14@syzkaller.appspotmail.com
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

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<pre>
commit d005f8c6588efcfbe88099b6edafc6f58c84a9c1 upstream.

A detach hung is possible when a race occurs between the detach process
and the ubi background thread. The following sequences outline the race:

  ubi thread: if (list_empty(&amp;ubi-&gt;works)...

  ubi detach: set_bit(KTHREAD_SHOULD_STOP, &amp;kthread-&gt;flags)
              =&gt; by kthread_stop()
              wake_up_process()
              =&gt; ubi thread is still running, so 0 is returned

  ubi thread: set_current_state(TASK_INTERRUPTIBLE)
              schedule()
              =&gt; ubi thread will never be scheduled again

  ubi detach: wait_for_completion()
              =&gt; hung task!

To fix that, we need to check kthread_should_stop() after we set the
task state, so the ubi thread will either see the stop bit and exit or
the task state is reset to runnable such that it isn't scheduled out
indefinitely.

Signed-off-by: Zhihao Cheng &lt;chengzhihao1@huawei.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Fixes: 801c135ce73d5df1ca ("UBI: Unsorted Block Images")
Reported-by: syzbot+853639d0cb16c31c7a14@syzkaller.appspotmail.com
Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
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