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dma-buf: fix stack corruption in dma_fence_chain_release 

We can't free up the chain using recursion or we run into a stack overflow.

Manually free up the dangling chain nodes to avoid recursion.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Fixes: 7bf60c52e0 ("dma-buf: add new dma_fence_chain container v7")
Link: https://patchwork.freedesktop.org/patch/321612/
This commit is contained in:
Christian König 2019-08-01 15:11:14 +02:00
parent 0dbd555a01
commit 92cb3e5980
1 changed files with 23 additions and 1 deletions
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24
drivers/dma-buf/dma-fence-chain.c
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@ -178,8 +178,30 @@ static bool dma_fence_chain_signaled(struct dma_fence *fence)
static void dma_fence_chain_release(struct dma_fence *fence)
{
struct dma_fence_chain *chain = to_dma_fence_chain(fence);
struct dma_fence *prev;
/* Manually unlink the chain as much as possible to avoid recursion
* and potential stack overflow.
*/
while ((prev = rcu_dereference_protected(chain->prev, true))) {
struct dma_fence_chain *prev_chain;
if (kref_read(&prev->refcount) > 1)
break;
prev_chain = to_dma_fence_chain(prev);
if (!prev_chain)
break;
/* No need for atomic operations since we hold the last
* reference to prev_chain.
*/
chain->prev = prev_chain->prev;
RCU_INIT_POINTER(prev_chain->prev, NULL);
dma_fence_put(prev);
}
dma_fence_put(prev);
dma_fence_put(rcu_dereference_protected(chain->prev, true));
dma_fence_put(chain->fence);
dma_fence_free(fence);
}