Hi David and Daniel,
Sorry but could you please help to check this issue?
Due to the function 'drm_gem_shmem_vmap' could return ERROR pointers
which will cause the kernel crash due to 'cirrus_fb_blit_rect' only
check the pointer.
Since the related code has been refactoring in mainline, so this issue
only happened in stable 5.10.y branch.
@Greg
I think it is probably not realistic to backport the related refactoring
from mainline directly, so I just give this bugfix patch only for 5.10.y
branch.
Thanks!
On 2021/12/29 22:51, Shile Zhang wrote:
On 2021/12/29 21:31, Greg Kroah-Hartman wrote:
On Wed, Dec 29, 2021 at 08:48:53AM +0800, Shile Zhang wrote:
On 2021/12/28 22:39, Greg Kroah-Hartman wrote:
On Tue, Dec 28, 2021 at 10:19:30PM +0800, Shile Zhang wrote:
On 2021/12/28 22:05, Greg Kroah-Hartman wrote:
On Tue, Dec 28, 2021 at 09:56:25PM +0800, Shile Zhang wrote:
On 2021/12/28 21:51, Greg Kroah-Hartman wrote:
On Tue, Dec 28, 2021 at 09:25:56PM +0800, Shile Zhang wrote:
The function drm_gem_shmem_vmap can returns error pointers as
well,
which could cause following kernel crash:
BUG: unable to handle page fault for address: fffffffffffffffc
PGD 1426a12067 P4D 1426a12067 PUD 1426a14067 PMD 0
Oops: 0000 [#1] SMP NOPTI
CPU: 12 PID: 3598532 Comm: stress-ng Kdump: loaded Not tainted
5.10.50.x86_64 #1
...
RIP: 0010:memcpy_toio+0x23/0x50
Code: 00 00 00 00 0f 1f 00 0f 1f 44 00 00 48 85 d2 74 28 40 f6
c7 01 75 2b 48 83 fa 01 76 06 40 f6 c7 02 75 17 48 89 d1 48 c1
e9 02 <f3> a5 f6 c2 02 74 02 66 a5 f6 c2 01 74 01 a4 c3 66 a5
48 83 ea 02
RSP: 0018:ffffafbf8a203c68 EFLAGS: 00010216
RAX: 0000000000000000 RBX: fffffffffffffffc RCX: 0000000000000200
RDX: 0000000000000800 RSI: fffffffffffffffc RDI: ffffafbf82000000
RBP: ffffafbf82000000 R08: 0000000000000002 R09: 0000000000000000
R10: 00000000000002b5 R11: 0000000000000000 R12: 0000000000000800
R13: ffff8a6801099300 R14: 0000000000000001 R15: 0000000000000300
FS: 00007f4a6bc5f740(0000) GS:ffff8a8641900000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffc CR3: 00000016d3874001 CR4: 00000000003606e0
Call Trace:
drm_fb_memcpy_dstclip+0x5e/0x80 [drm_kms_helper]
cirrus_fb_blit_rect.isra.0+0xb7/0xe0 [cirrus]
cirrus_pipe_update+0x9f/0xa8 [cirrus]
drm_atomic_helper_commit_planes+0xb8/0x220 [drm_kms_helper]
drm_atomic_helper_commit_tail+0x42/0x80 [drm_kms_helper]
commit_tail+0xce/0x130 [drm_kms_helper]
drm_atomic_helper_commit+0x113/0x140 [drm_kms_helper]
drm_client_modeset_commit_atomic+0x1c4/0x200 [drm]
drm_client_modeset_commit_locked+0x53/0x80 [drm]
drm_client_modeset_commit+0x24/0x40 [drm]
drm_fbdev_client_restore+0x48/0x85 [drm_kms_helper]
drm_client_dev_restore+0x64/0xb0 [drm]
drm_release+0xf2/0x110 [drm]
__fput+0x96/0x240
task_work_run+0x5c/0x90
exit_to_user_mode_loop+0xce/0xd0
exit_to_user_mode_prepare+0x6a/0x70
syscall_exit_to_user_mode+0x12/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f4a6bd82c2b
Fixes: ab3e023b1b4c9 ("drm/cirrus: rewrite and modernize driver.")
CC: stable@xxxxxxxxxxxxxxx
Reported-by: Wen Kang <kw01107137@xxxxxxxxxxxxxxx>
Signed-off-by: Shile Zhang <shile.zhang@xxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/tiny/cirrus.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
What is the git commit id of this patch in Linus's tree?
Sorry, I checked that this issue seems fixed by the improvement
in following
series:
https://patchwork.freedesktop.org/series/82217/
I do not understand, that is a huge patch series. What individual
commit in Linus's tree resolves this?
Sorry,
1. This crash only happened in 5.10.y tree now, which fixed in
Linus's tree
by refactoring in above huge series.
Which specific patch resolved the issue?
2. It's hard to get the individual commit to fix this issue from that
series. So I try to send this simple fix help to fix only for
5.10.y, which
is needless to Linus's tree.
'git bisect' should be able to help you out.
Thanks for your guidance!
3. If this patch is not OK for stable tree, Could you please help to
backport the correct fix from Linus's tree in next version of 5.10.y?
If you can provide the commit id of the fix, sure.
Thanks!
I think it is this commit, which refactor the drm_gem_shmem_vmap
makes the
pointer returned by new added parameter.
https://github.com/torvalds/linux/commit/49a3f51dfeeecb52c5aa28c5cb9592fe5e39bf95
Have you tested it to be sure? If so, can you please provide a
backported version that works? As-is, it does not apply at all.
Yes, we've tested that the mainline code fixed this issue.
But sorry, I have not backported the bugfix from mainline due to that a
huge series for code refactoring, with more dependencies an conflicts.
So I just work out a simple patch help to fix the crash.
Note, if this is to bit of a change for a stable tree (and I think it
is), your original patch might be correct, but I need some acks from the
subsystem maintainers before I can take such a thing. I also need a lot
of documentation in the changelog text about why this is a 5.10-only
thing.
Since the original guilty commit (ab3e023b1b4c9) merge in 5.2-rc1, and
Thomas's refactoring series (49a3f51dfee) just merged in 5.11-rc1. So
this issue only happened in stable 5.4 & 5.10 only.
@David @Daniel
Could you guys also help to check this crash issue?
Thanks all!
thanks,
greg k-h
