linux-stable.git/drivers/tty/vt, branch v4.19.321

vt: fix memory overlapping when deleting chars in the buffer

2024-04-13T10:50:09+00:00

commit 39cdb68c64d84e71a4a717000b6e5de208ee60cc upstream.

A memory overlapping copy occurs when deleting a long line. This memory
overlapping copy can cause data corruption when scr_memcpyw is optimized
to memcpy because memcpy does not ensure its behavior if the destination
buffer overlaps with the source buffer. The line buffer is not always
broken, because the memcpy utilizes the hardware acceleration, whose
result is not deterministic.

Fix this problem by using replacing the scr_memcpyw with scr_memmovew.

Fixes: 81732c3b2fed ("tty vt: Fix line garbage in virtual console on command line edition")
Cc: stable 
Signed-off-by: Yangxi Xiang 
Link: https://lore.kernel.org/r/20220628093322.5688-1-xyangxi5@gmail.com
[ KN: vc_state is not a separate structure in LTS v4.19, v5.4. Adjusted the patch
  accordingly by using vc_x instead of state.x for backport. ]
Signed-off-by: Kuntal Nayak 
Signed-off-by: Greg Kroah-Hartman

vt: fix unicode buffer corruption when deleting characters

2024-04-13T10:50:09+00:00

commit 1581dafaf0d34bc9c428a794a22110d7046d186d upstream.

This is the same issue that was fixed for the VGA text buffer in commit
39cdb68c64d8 ("vt: fix memory overlapping when deleting chars in the
buffer"). The cure is also the same i.e. replace memcpy() with memmove()
due to the overlaping buffers.

Signed-off-by: Nicolas Pitre 
Fixes: 81732c3b2fed ("tty vt: Fix line garbage in virtual console on command line edition")
Cc: stable 
Link: https://lore.kernel.org/r/sn184on2-3p0q-0qrq-0218-895349s4753o@syhkavp.arg
Signed-off-by: Greg Kroah-Hartman

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

2023-05-30T11:42:13+00:00

[ Upstream commit 8fb9ea65c9d1338b0d2bb0a9122dc942cdd32357 ]

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 
Signed-off-by: Sasha Levin

vc_screen: rewrite vcs_size to accept vc, not inode

2023-05-30T11:42:13+00:00

[ Upstream commit 71d4abfab322e827a75304431fe0fad3c805cb80 ]

It is weird to fetch the information from the inode over and over. Read
and write already have the needed information, so rewrite vcs_size to
accept a vc, attr and unicode and adapt vcs_lseek to that.

Also make sure all sites check the return value of vcs_size for errors.

And document it using kernel-doc.

Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20200818085706.12163-5-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman 
Stable-dep-of: 8fb9ea65c9d1 ("vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF")
Signed-off-by: Sasha Levin

vc_screen: modify vcs_size() handling in vcs_read()

2023-03-11T15:31:59+00:00

[ Upstream commit 46d733d0efc79bc8430d63b57ab88011806d5180 ]

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 
Signed-off-by: Sasha Levin

vc_screen: don't clobber return value in vcs_read

2023-03-03T10:40:07+00:00

commit ae3419fbac845b4d3f3a9fae4cc80c68d82cdf6e upstream.

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 
Signed-off-by: Greg Kroah-Hartman

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

2023-02-22T11:47:13+00:00

[ Upstream commit 226fae124b2dac217ea5436060d623ff3385bc34 ]

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 
Signed-off-by: Sasha Levin

vt: Clear selection before changing the font

2022-09-15T10:17:03+00:00

commit 566f9c9f89337792070b5a6062dff448b3e7977f upstream.

When changing the console font with ioctl(KDFONTOP) the new font size
can be bigger than the previous font. A previous selection may thus now
be outside of the new screen size and thus trigger out-of-bounds
accesses to graphics memory if the selection is removed in
vc_do_resize().

Prevent such out-of-memory accesses by dropping the selection before the
various con_font_set() console handlers are called.

Reported-by: syzbot+14b0e8f3fd1612e35350@syzkaller.appspotmail.com
Cc: stable 
Tested-by: Khalid Masum 
Signed-off-by: Helge Deller 
Link: https://lore.kernel.org/r/YuV9apZGNmGfjcor@p100
Signed-off-by: Greg Kroah-Hartman

tty: vt: initialize unicode screen buffer

2022-08-25T09:14:53+00:00

commit af77c56aa35325daa2bc2bed5c2ebf169be61b86 upstream.

syzbot reports kernel infoleak at vcs_read() [1], for buffer can be read
immediately after resize operation. Initialize buffer using kzalloc().

  ----------
  #include 
  #include 
  #include 
  #include 

  int main(int argc, char *argv[])
  {
    struct fb_var_screeninfo var = { };
    const int fb_fd = open("/dev/fb0", 3);
    ioctl(fb_fd, FBIOGET_VSCREENINFO, &var);
    var.yres = 0x21;
    ioctl(fb_fd, FBIOPUT_VSCREENINFO, &var);
    return read(open("/dev/vcsu", O_RDONLY), &var, sizeof(var)) == -1;
  }
  ----------

Link: https://syzkaller.appspot.com/bug?extid=31a641689d43387f05d3 [1]
Cc: stable 
Reported-by: syzbot 
Reviewed-by: Jiri Slaby 
Signed-off-by: Tetsuo Handa 
Link: https://lore.kernel.org/r/4ef053cf-e796-fb5e-58b7-3ae58242a4ad@I-love.SAKURA.ne.jp
Signed-off-by: Greg Kroah-Hartman

tty: drivers/tty/, stop using tty_schedule_flip()

2022-07-29T15:10:37+00:00

commit 5f6a85158ccacc3f09744b3aafe8b11ab3b6c6f6 upstream.

Since commit a9c3f68f3cd8d (tty: Fix low_latency BUG) in 2014,
tty_flip_buffer_push() is only a wrapper to tty_schedule_flip(). We are
going to remove the latter (as it is used less), so call the former in
drivers/tty/.

Cc: Vladimir Zapolskiy 
Reviewed-by: Johan Hovold 
Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20211122111648.30379-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman