Vulnerability details

In the Linux kernel, the following vulnerability has been resolved: xfrm: fix stale skb->prev after async crypto steals a GSO segment skb_gso_segment() leaves the segment list head with ->prev pointing at the last segment, an invariant validate_xmit_skb_list() relies on when it sets its tail pointer (tail = skb->prev). When validate_xmit_xfrm() walks a GSO list and some segments are stolen by async crypto (->xmit() returns -EINPROGRESS), those segments are unlinked from the list but the head ->prev is never updated. If the last segment is the one stolen, the returned head still has ->prev pointing at it, even though it is now owned by the crypto engine and may be freed. validate_xmit_skb_list() later does tail->next = skb, writing through that stale pointer -- a use-after-free. Repoint skb->prev at the last retained segment before returning.

• https://git.kernel.org/stable/c/4e695742396be18d5291c310a3d7c450959d647a
• https://git.kernel.org/stable/c/4927ab8a8acc8db4fad33e803d1d35e0b16cef83
• https://git.kernel.org/stable/c/b58731e0570bfd3989999fc2baf9ee4fecd5bec6
• https://git.kernel.org/stable/c/33e1b0d25ca0d2818c635ff80e6aa0d295e08a98
• https://git.kernel.org/stable/c/bbca7cc3b2b4b10afbfee99b81d9ee78f5423046
• https://git.kernel.org/stable/c/3f4c3919baf0944ad96580467c302bc6c7758b00