From: Yonglong Li Date: Thu, 17 Mar 2022 22:09:53 +0000 (-0700) Subject: mptcp: Fix crash due to tcp_tsorted_anchor was initialized before release skb X-Git-Tag: v5.15.73~647 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=af61a8f7603926c26158153d0a0755764d82657c;p=platform%2Fkernel%2Flinux-rpi.git mptcp: Fix crash due to tcp_tsorted_anchor was initialized before release skb commit 3ef3905aa3b5b3e222ee6eb0210bfd999417a8cc upstream. Got crash when doing pressure test of mptcp: =========================================================================== dst_release: dst:ffffa06ce6e5c058 refcnt:-1 kernel tried to execute NX-protected page - exploit attempt? (uid: 0) BUG: unable to handle kernel paging request at ffffa06ce6e5c058 PGD 190a01067 P4D 190a01067 PUD 43fffb067 PMD 22e403063 PTE 8000000226e5c063 Oops: 0011 [#1] SMP PTI CPU: 7 PID: 7823 Comm: kworker/7:0 Kdump: loaded Tainted: G E Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.2.1 04/01/2014 Call Trace: ? skb_release_head_state+0x68/0x100 ? skb_release_all+0xe/0x30 ? kfree_skb+0x32/0xa0 ? mptcp_sendmsg_frag+0x57e/0x750 ? __mptcp_retrans+0x21b/0x3c0 ? __switch_to_asm+0x35/0x70 ? mptcp_worker+0x25e/0x320 ? process_one_work+0x1a7/0x360 ? worker_thread+0x30/0x390 ? create_worker+0x1a0/0x1a0 ? kthread+0x112/0x130 ? kthread_flush_work_fn+0x10/0x10 ? ret_from_fork+0x35/0x40 =========================================================================== In __mptcp_alloc_tx_skb skb was allocated and skb->tcp_tsorted_anchor will be initialized, in under memory pressure situation sk_wmem_schedule will return false and then kfree_skb. In this case skb->_skb_refdst is not null because_skb_refdst and tcp_tsorted_anchor are stored in the same mem, and kfree_skb will try to release dst and cause crash. Fixes: f70cad1085d1 ("mptcp: stop relying on tcp_tx_skb_cache") Reviewed-by: Paolo Abeni Signed-off-by: Yonglong Li Signed-off-by: Mat Martineau Link: https://lore.kernel.org/r/20220317220953.426024-1-mathew.j.martineau@linux.intel.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 5df60a4..47f359d 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1246,6 +1246,7 @@ static struct sk_buff *__mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, g tcp_skb_entail(ssk, skb); return skb; } + tcp_skb_tsorted_anchor_cleanup(skb); kfree_skb(skb); return NULL; }