diff options
| author | Ashutosh Desai <ashutoshdesai993@gmail.com> | 2026-04-15 05:00:00 +0000 |
|---|---|---|
| committer | Maíra Canal <mcanal@igalia.com> | 2026-04-19 19:07:29 -0300 |
| commit | fb44d589bf3148e13452185a6e772a7efbf2d684 (patch) | |
| tree | 9bc7c0842139ab281ec3abfb896f3c3af72666ad /drivers | |
| parent | 4a92ef0c57df610ba0b2eb7f308c5472020ce8ea (diff) | |
drm/v3d: Reject empty multisync extension to prevent infinite loop
v3d_get_extensions() walks a userspace-provided singly-linked list of
ioctl extensions without any bound on the chain length. A local user
can craft a self-referential extension (ext->next == &ext) with zero
in_sync_count and out_sync_count, which bypasses the existing duplicate-
extension guard:
if (se->in_sync_count || se->out_sync_count)
return -EINVAL;
The guard never fires because v3d_get_multisync_post_deps() returns
immediately when count is zero, leaving both fields at zero on every
iteration. The result is an infinite loop in kernel context, blocking
the calling thread and pegging a CPU core indefinitely.
Fix this by rejecting a multisync extension where both in_sync_count
and out_sync_count are zero in v3d_get_multisync_submit_deps(). An
empty multisync carries no synchronization information and serves no
useful purpose, so returning -EINVAL for such an extension is the
correct defense against this attack vector.
Fixes: e4165ae8304e ("drm/v3d: add multiple syncobjs support")
Cc: stable@vger.kernel.org
Signed-off-by: Ashutosh Desai <ashutoshdesai993@gmail.com>
Link: https://patch.msgid.link/20260415050000.3816128-1-ashutoshdesai993@gmail.com
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/gpu/drm/v3d/v3d_submit.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/gpu/drm/v3d/v3d_submit.c b/drivers/gpu/drm/v3d/v3d_submit.c index 18f2bf1fe89f..fc74351efad5 100644 --- a/drivers/gpu/drm/v3d/v3d_submit.c +++ b/drivers/gpu/drm/v3d/v3d_submit.c @@ -393,6 +393,11 @@ v3d_get_multisync_submit_deps(struct drm_file *file_priv, if (multisync.pad) return -EINVAL; + if (!multisync.in_sync_count && !multisync.out_sync_count) { + drm_dbg(&v3d->drm, "Empty multisync extension\n"); + return -EINVAL; + } + ret = v3d_get_multisync_post_deps(file_priv, se, multisync.out_sync_count, multisync.out_syncs); if (ret) |