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authorMagnus Karlsson <magnus.karlsson@intel.com>2020-10-27 13:32:01 +0100
committerDaniel Borkmann <daniel@iogearbox.net>2020-10-29 15:19:56 +0100
commite5e1a4bc916d29958c3b587354293738fcb984d7 (patch)
treec9a7a0138ea00d9147bf2972fc103150742ad48f /tools/bpf
parent821f5c90130d15f8f725412d714d05df3b9e0fac (diff)
xsk: Fix possible memory leak at socket close
Fix a possible memory leak at xsk socket close that is caused by the refcounting of the umem object being wrong. The reference count of the umem was decremented only after the pool had been freed. Note that if the buffer pool is destroyed, it is important that the umem is destroyed after the pool, otherwise the umem would disappear while the driver is still running. And as the buffer pool needs to be destroyed in a work queue, the umem is also (if its refcount reaches zero) destroyed after the buffer pool in that same work queue. What was missing is that the refcount also needs to be decremented when the pool is not freed and when the pool has not even been created. The first case happens when the refcount of the pool is higher than 1, i.e. it is still being used by some other socket using the same device and queue id. In this case, it is safe to decrement the refcount of the umem outside of the work queue as the umem will never be freed because the refcount of the umem is always greater than or equal to the refcount of the buffer pool. The second case is if the buffer pool has not been created yet, i.e. the socket was closed before it was bound but after the umem was created. In this case, it is safe to destroy the umem outside of the work queue, since there is no pool that can use it by definition. Fixes: 1c1efc2af158 ("xsk: Create and free buffer pool independently from umem") Reported-by: syzbot+eb71df123dc2be2c1456@syzkaller.appspotmail.com Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Björn Töpel <bjorn.topel@intel.com> Link: https://lore.kernel.org/bpf/1603801921-2712-1-git-send-email-magnus.karlsson@gmail.com
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