diff options
| author | Robin Murphy <robin.murphy@arm.com> | 2019-10-28 23:08:25 +0300 |
|---|---|---|
| committer | Rob Herring <robh@kernel.org> | 2019-10-29 21:18:17 +0300 |
| commit | f70744c68779c8a72a0c82294e3233b994af656d (patch) | |
| tree | 96605060d4e9da19aaa30a854b001277da6401b2 /drivers/gpu/drm/panfrost | |
| parent | 6f39188c9d5f81af7a3bc687636b7abc9629ee27 (diff) | |
| download | linux-f70744c68779c8a72a0c82294e3233b994af656d.tar.xz | |
drm/panfrost: Don't dereference bogus MMU pointers
It seems that killing an application while faults are occurring
(particularly with a GPU in FPGA at a whopping 40MHz) can lead to
handling a lingering page fault after all the address space contexts
have already been freed. In this situation, the LRU list is empty so
addr_to_drm_mm_node() ends up dereferencing the list head as if it were
a struct panfrost_mmu entry; this leaves "mmu->as" actually pointing at
the pfdev->alloc_mask bitmap, which is also empty, and given that the
fault has a high likelihood of being in AS0, hilarity ensues.
Sadly, the cleanest solution seems to involve another goto. Oh well, at
least it's robust...
Fixes: 65e51e30d862 ("drm/panfrost: Prevent race when handling page fault")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/9a0b09e6b5851f0d4428b72dd6b8b4c0d0ef4206.1572293305.git.robin.murphy@arm.com
Diffstat (limited to 'drivers/gpu/drm/panfrost')
| -rw-r--r-- | drivers/gpu/drm/panfrost/panfrost_mmu.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c index 87e7963b8adf..a3ed64a1f15e 100644 --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c @@ -406,11 +406,11 @@ addr_to_drm_mm_node(struct panfrost_device *pfdev, int as, u64 addr) spin_lock(&pfdev->as_lock); list_for_each_entry(mmu, &pfdev->as_lru_list, list) { if (as == mmu->as) - break; + goto found_mmu; } - if (as != mmu->as) - goto out; + goto out; +found_mmu: priv = container_of(mmu, struct panfrost_file_priv, mmu); spin_lock(&priv->mm_lock); |