linux.git/drivers/tty/vt/vc_screen.c, branch for-next

move asm/unaligned.h to linux/unaligned.h

2024-10-02T21:23:23+00:00

asm/unaligned.h is always an include of asm-generic/unaligned.h;
might as well move that thing to linux/unaligned.h and include
that - there's nothing arch-specific in that header.

auto-generated by the following:

for i in `git grep -l -w asm/unaligned.h`; do
	sed -i -e "s/asm\/unaligned.h/linux\/unaligned.h/" $i
done
for i in `git grep -l -w asm-generic/unaligned.h`; do
	sed -i -e "s/asm-generic\/unaligned.h/linux\/unaligned.h/" $i
done
git mv include/asm-generic/unaligned.h include/linux/unaligned.h
git mv tools/include/asm-generic/unaligned.h tools/include/linux/unaligned.h
sed -i -e "/unaligned.h/d" include/asm-generic/Kbuild
sed -i -e "s/__ASM_GENERIC/__LINUX/" include/linux/unaligned.h tools/include/linux/unaligned.h

printk: Change type of CONFIG_BASE_SMALL to bool

2024-05-06T15:39:09+00:00

CONFIG_BASE_SMALL is currently a type int but is only used as a boolean.

So, change its type to bool and adapt all usages:
CONFIG_BASE_SMALL == 0 becomes !IS_ENABLED(CONFIG_BASE_SMALL) and
CONFIG_BASE_SMALL != 0 becomes  IS_ENABLED(CONFIG_BASE_SMALL).

Reviewed-by: Petr Mladek 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Masahiro Yamada 
Signed-off-by: Yoann Congal 
Link: https://lore.kernel.org/r/20240505080343.1471198-3-yoann.congal@smile.fr
Signed-off-by: Petr Mladek

tty: vc_screen: make vc_class constant

2023-10-07T09:18:51+00:00

Now that the driver core allows for struct class to be in read-only
memory, making all 'class' structures to be declared at build time
placing them into read-only memory, instead of having to be dynamically
allocated at load time.

Cc: Jiri Slaby 
Link: https://lore.kernel.org/r/2023100549-sixth-anger-ac34@gregkh
Signed-off-by: Greg Kroah-Hartman

tty: stop using ndash in kernel-doc

2023-10-03T12:31:16+00:00

An ndash used instead of a single dash renders a bullet to the result.
So use only single dashes in kernel-doc.

Signed-off-by: "Jiri Slaby (SUSE)" 
Link: https://lore.kernel.org/r/20230919085156.1578-11-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman

vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF

2023-05-13T11:01:13+00:00

After a call to console_unlock() in vcs_write() the vc_data struct can be
freed by vc_port_destruct(). Because of that, the struct vc_data pointer
must be reloaded in the while loop in vcs_write() after console_lock() to
avoid a UAF when vcs_size() is called.

Syzkaller reported a UAF in vcs_size().

BUG: KASAN: slab-use-after-free in vcs_size (drivers/tty/vt/vc_screen.c:215)
Read of size 4 at addr ffff8880beab89a8 by task repro_vcs_size/4119

Call Trace:
 
__asan_report_load4_noabort (mm/kasan/report_generic.c:380)
vcs_size (drivers/tty/vt/vc_screen.c:215)
vcs_write (drivers/tty/vt/vc_screen.c:664)
vfs_write (fs/read_write.c:582 fs/read_write.c:564)
...
 

Allocated by task 1213:
kmalloc_trace (mm/slab_common.c:1064)
vc_allocate (./include/linux/slab.h:559 ./include/linux/slab.h:680
    drivers/tty/vt/vt.c:1078 drivers/tty/vt/vt.c:1058)
con_install (drivers/tty/vt/vt.c:3334)
tty_init_dev (drivers/tty/tty_io.c:1303 drivers/tty/tty_io.c:1415
    drivers/tty/tty_io.c:1392)
tty_open (drivers/tty/tty_io.c:2082 drivers/tty/tty_io.c:2128)
chrdev_open (fs/char_dev.c:415)
do_dentry_open (fs/open.c:921)
vfs_open (fs/open.c:1052)
...

Freed by task 4116:
kfree (mm/slab_common.c:1016)
vc_port_destruct (drivers/tty/vt/vt.c:1044)
tty_port_destructor (drivers/tty/tty_port.c:296)
tty_port_put (drivers/tty/tty_port.c:312)
vt_disallocate_all (drivers/tty/vt/vt_ioctl.c:662 (discriminator 2))
vt_ioctl (drivers/tty/vt/vt_ioctl.c:903)
tty_ioctl (drivers/tty/tty_io.c:2778)
...

The buggy address belongs to the object at ffff8880beab8800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 424 bytes inside of
 freed 1024-byte region [ffff8880beab8800, ffff8880beab8c00)

The buggy address belongs to the physical page:
page:00000000afc77580 refcount:1 mapcount:0 mapping:0000000000000000
    index:0x0 pfn:0xbeab8
head:00000000afc77580 order:3 entire_mapcount:0 nr_pages_mapped:0
    pincount:0
flags: 0xfffffc0010200(slab|head|node=0|zone=1|lastcpupid=0x1fffff)
page_type: 0xffffffff()
raw: 000fffffc0010200 ffff888100042dc0 ffffea000426de00 dead000000000002
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880beab8880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880beab8900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880beab8980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff8880beab8a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880beab8a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Disabling lock debugging due to kernel taint

Fixes: ac751efa6a0d ("console: rename acquire/release_console_sem() to console_lock/unlock()")
Cc: stable 
Reported-by: syzkaller 
Signed-off-by: George Kennedy 
Reviewed-by: Thomas Weißschuh 
Link: https://lore.kernel.org/r/1683889728-10411-1-git-send-email-george.kennedy@oracle.com
Signed-off-by: Greg Kroah-Hartman

driver core: class: remove module * from class_create()

2023-03-17T14:16:33+00:00

The module pointer in class_create() never actually did anything, and it
shouldn't have been requred to be set as a parameter even if it did
something.  So just remove it and fix up all callers of the function in
the kernel tree at the same time.

Cc: "Rafael J. Wysocki" 
Acked-by: Benjamin Tissoires 
Link: https://lore.kernel.org/r/20230313181843.1207845-4-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman

vc_screen: don't clobber return value in vcs_read

2023-02-28T02:35:28+00:00

Commit 226fae124b2d ("vc_screen: move load of struct vc_data pointer in
vcs_read() to avoid UAF") moved the call to vcs_vc() into the loop.

While doing this it also moved the unconditional assignment of

	ret = -ENXIO;

This unconditional assignment was valid outside the loop but within it
it clobbers the actual value of ret.

To avoid this only assign "ret = -ENXIO" when actually needed.

[ Also, the 'goto unlock_out" needs to be just a "break", so that it
  does the right thing when it exits on later iterations when partial
  success has happened - Linus ]

Reported-by: Storm Dragon 
Link: https://lore.kernel.org/lkml/Y%2FKS6vdql2pIsCiI@hotmail.com/
Fixes: 226fae124b2d ("vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF")
Signed-off-by: Thomas Weißschuh 
Link: https://lore.kernel.org/lkml/64981d94-d00c-4b31-9063-43ad0a384bde@t-8ch.de/
Signed-off-by: Linus Torvalds

vc_screen: modify vcs_size() handling in vcs_read()

2023-02-28T00:10:38+00:00

Restore the vcs_size() handling in vcs_read() to what
it had been in previous version.

Fixes: 226fae124b2d ("vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF")
Suggested-by: Jiri Slaby 
Signed-off-by: George Kennedy 
Signed-off-by: Linus Torvalds

vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF

2023-01-31T14:51:52+00:00

After a call to console_unlock() in vcs_read() the vc_data struct can be
freed by vc_deallocate(). Because of that, the struct vc_data pointer
load must be done at the top of while loop in vcs_read() to avoid a UAF
when vcs_size() is called.

Syzkaller reported a UAF in vcs_size().

BUG: KASAN: use-after-free in vcs_size (drivers/tty/vt/vc_screen.c:215)
Read of size 4 at addr ffff8881137479a8 by task 4a005ed81e27e65/1537

CPU: 0 PID: 1537 Comm: 4a005ed81e27e65 Not tainted 6.2.0-rc5 #1
Hardware name: Red Hat KVM, BIOS 1.15.0-2.module
Call Trace:
  
__asan_report_load4_noabort (mm/kasan/report_generic.c:350)
vcs_size (drivers/tty/vt/vc_screen.c:215)
vcs_read (drivers/tty/vt/vc_screen.c:415)
vfs_read (fs/read_write.c:468 fs/read_write.c:450)
...
  

Allocated by task 1191:
...
kmalloc_trace (mm/slab_common.c:1069)
vc_allocate (./include/linux/slab.h:580 ./include/linux/slab.h:720
     drivers/tty/vt/vt.c:1128 drivers/tty/vt/vt.c:1108)
con_install (drivers/tty/vt/vt.c:3383)
tty_init_dev (drivers/tty/tty_io.c:1301 drivers/tty/tty_io.c:1413
     drivers/tty/tty_io.c:1390)
tty_open (drivers/tty/tty_io.c:2080 drivers/tty/tty_io.c:2126)
chrdev_open (fs/char_dev.c:415)
do_dentry_open (fs/open.c:883)
vfs_open (fs/open.c:1014)
...

Freed by task 1548:
...
kfree (mm/slab_common.c:1021)
vc_port_destruct (drivers/tty/vt/vt.c:1094)
tty_port_destructor (drivers/tty/tty_port.c:296)
tty_port_put (drivers/tty/tty_port.c:312)
vt_disallocate_all (drivers/tty/vt/vt_ioctl.c:662 (discriminator 2))
vt_ioctl (drivers/tty/vt/vt_ioctl.c:903)
tty_ioctl (drivers/tty/tty_io.c:2776)
...

The buggy address belongs to the object at ffff888113747800
  which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 424 bytes inside of
  1024-byte region [ffff888113747800, ffff888113747c00)

The buggy address belongs to the physical page:
page:00000000b3fe6c7c refcount:1 mapcount:0 mapping:0000000000000000
     index:0x0 pfn:0x113740
head:00000000b3fe6c7c order:3 compound_mapcount:0 subpages_mapcount:0
     compound_pincount:0
anon flags: 0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff)
raw: 0017ffffc0010200 ffff888100042dc0 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff888113747880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff888113747900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888113747980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                   ^
  ffff888113747a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff888113747a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Disabling lock debugging due to kernel taint

Fixes: ac751efa6a0d ("console: rename acquire/release_console_sem() to console_lock/unlock()")
Reported-by: syzkaller 
Suggested-by: Jiri Slaby 
Signed-off-by: George Kennedy 
Link: https://lore.kernel.org/r/1674577014-12374-1-git-send-email-george.kennedy@oracle.com
Signed-off-by: Greg Kroah-Hartman

Revert "vc_screen: extract vcs_read_buf_header"

2020-08-24T17:51:56+00:00

This reverts commit b1c32fcfadf5593ab7a63261cc8a5747c36e627e, because
Syzkaller reports a use-after-free, a write in vcs_read:

BUG: KASAN: use-after-free in vcs_read_buf drivers/tty/vt/vc_screen.c:357 [inline]
BUG: KASAN: use-after-free in vcs_read+0xaa7/0xb40 drivers/tty/vt/vc_screen.c:449
Write of size 2 at addr ffff8880a8014000 by task syz-executor.5/16936
CPU: 1 PID: 16936 Comm: syz-executor.5 Not tainted 5.9.0-rc1-next-20200820-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
...
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 vcs_read_buf drivers/tty/vt/vc_screen.c:357 [inline]
 vcs_read+0xaa7/0xb40 drivers/tty/vt/vc_screen.c:449

There are two issues with the patch:
1) vcs_read rounds the 'count' *up* to an even number. So if we read odd
   bytes from the header (3 bytes in the reproducer), the second byte of
   a (2-byte/ushort) write to temporary con_buf won't fit. It is because
   with the patch applied, we only subtract the real number read (3 bytes)
   and not the whole header (4 bytes).

2) in this scenario, we perform unaligned accesses now: there are
   2-byte/ushort writes to odd addresses. Due to the same reason as
   above.

Revert this for now, re-think and retry later.

Signed-off-by: Jiri Slaby 
Reported-by: syzbot+ad1f53726c3bd11180cb@syzkaller.appspotmail.com
Fixes: b1c32fcfadf5 ("vc_screen: extract vcs_read_buf_header")
Cc: akpm@linux-foundation.org
Cc: nico@fluxnic.net
Link: https://lore.kernel.org/r/20200824095425.4376-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman