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drm/vc4: Protect madv read in vc4_gem_object_mmap() with madv_lock

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The mmap callback reads bo->madv without holding madv_lock, racing with
concurrent DRM_IOCTL_VC4_GEM_MADVISE calls that modify the field under
the same lock. Add the missing locking to prevent the data race.

Fixes: b9f19259b8 ("drm/vc4: Add the DRM_IOCTL_VC4_GEM_MADVISE ioctl")
Reviewed-by: Melissa Wen <mwen@igalia.com>
Link: https://patch.msgid.link/20260330-vc4-misc-fixes-v1-4-92defc940a29@igalia.com
Signed-off-by: Maíra Canal <mcanal@igalia.com>
This commit is contained in:
Maíra Canal 2026-03-30 14:51:46 -03:00
parent 9525d169e5
commit 338c56050d
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GPG Key ID: 3FF30E8A7688FAAA
1 changed files with 3 additions and 0 deletions
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3
drivers/gpu/drm/vc4/vc4_bo.c
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@ -738,12 +738,15 @@ static int vc4_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_struct
return -EINVAL;
}
mutex_lock(&bo->madv_lock);
if (bo->madv != VC4_MADV_WILLNEED) {
DRM_DEBUG("mmapping of %s BO not allowed\n",
bo->madv == VC4_MADV_DONTNEED ?
"purgeable" : "purged");
mutex_unlock(&bo->madv_lock);
return -EINVAL;
}
mutex_unlock(&bo->madv_lock);
return drm_gem_dma_mmap(&bo->base, vma);
}