mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-18 17:54:13 +08:00
d0b2c5334f
... not only when the dma-buf is freshly created. In contrived examples someone else could have exported/imported the dma-buf already and handed us the gem object with a flink name. If such on object gets reexported as a dma_buf we won't have it in the handle cache already, which breaks the guarantee that for dma-buf imports we always hand back an existing handle if there is one. This is exercised by igt/prime_self_import/with_one_bo_two_files Now if we extend the locked sections just a notch more we can also plug th racy buf/handle cache setup in handle_to_fd: If evil userspace races a concurrent gem close against a prime export operation we can end up tearing down the gem handle before the dma buf handle cache is set up. When handle_to_fd gets around to adding the handle to the cache there will be no one left to clean it up, effectily leaking the bo (and the dma-buf, since the handle cache holds a ref on the dma-buf): Thread A Thread B handle_to_fd: lookup gem object from handle creates new dma_buf gem_close on the same handle obj->dma_buf is set, but file priv buf handle cache has no entry obj->handle_count drops to 0 drm_prime_add_buf_handle sets up the handle cache -> We have a dma-buf reference in the handle cache, but since the handle_count of the gem object already dropped to 0 no on will clean it up. When closing the drm device fd we'll hit the WARN_ON in drm_prime_destroy_file_private. The important change is to extend the critical section of the filp->prime.lock to cover the gem handle lookup. This serializes with a concurrent gem handle close. This leak is exercised by igt/prime_self_import/export-vs-gem_close-race Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Dave Airlie <airlied@redhat.com> |
||
---|---|---|
.. | ||
acpi | ||
asm-generic | ||
clocksource | ||
crypto | ||
drm | ||
dt-bindings | ||
keys | ||
kvm | ||
linux | ||
math-emu | ||
media | ||
memory | ||
misc | ||
net | ||
pcmcia | ||
ras | ||
rdma | ||
rxrpc | ||
scsi | ||
sound | ||
target | ||
trace | ||
uapi | ||
video | ||
xen | ||
Kbuild |