This is a note to let you know that I've just added the patch titled bpf, sockmap: Fix repeated calls to sock_put() when msg has more_data to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: bpf-sockmap-fix-repeated-calls-to-sock_put-when-msg-.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 40aae9b3ece957c041cc1b4c83740934b8a61e2f Author: Pengcheng Yang <yangpc@xxxxxxxxxx> Date: Tue Nov 29 18:40:38 2022 +0800 bpf, sockmap: Fix repeated calls to sock_put() when msg has more_data [ Upstream commit 7a9841ca025275b5b0edfb0b618934abb6ceec15 ] In tcp_bpf_send_verdict() redirection, the eval variable is assigned to __SK_REDIRECT after the apply_bytes data is sent, if msg has more_data, sock_put() will be called multiple times. We should reset the eval variable to __SK_NONE every time more_data starts. This causes: IPv4: Attempt to release TCP socket in state 1 00000000b4c925d7 ------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 5 PID: 4482 at lib/refcount.c:25 refcount_warn_saturate+0x7d/0x110 Modules linked in: CPU: 5 PID: 4482 Comm: sockhash_bypass Kdump: loaded Not tainted 6.0.0 #1 Hardware name: Red Hat KVM, BIOS 1.11.0-2.el7 04/01/2014 Call Trace: <TASK> __tcp_transmit_skb+0xa1b/0xb90 ? __alloc_skb+0x8c/0x1a0 ? __kmalloc_node_track_caller+0x184/0x320 tcp_write_xmit+0x22a/0x1110 __tcp_push_pending_frames+0x32/0xf0 do_tcp_sendpages+0x62d/0x640 tcp_bpf_push+0xae/0x2c0 tcp_bpf_sendmsg_redir+0x260/0x410 ? preempt_count_add+0x70/0xa0 tcp_bpf_send_verdict+0x386/0x4b0 tcp_bpf_sendmsg+0x21b/0x3b0 sock_sendmsg+0x58/0x70 __sys_sendto+0xfa/0x170 ? xfd_validate_state+0x1d/0x80 ? switch_fpu_return+0x59/0xe0 __x64_sys_sendto+0x24/0x30 do_syscall_64+0x37/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd Fixes: cd9733f5d75c ("tcp_bpf: Fix one concurrency problem in the tcp_bpf_send_verdict function") Signed-off-by: Pengcheng Yang <yangpc@xxxxxxxxxx> Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Acked-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/bpf/1669718441-2654-2-git-send-email-yangpc@xxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index 809ee0f32d59..027f7f9256e1 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -316,7 +316,7 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock, bool cork = false, enospc = sk_msg_full(msg); struct sock *sk_redir; u32 tosend, origsize, sent, delta = 0; - u32 eval = __SK_NONE; + u32 eval; int ret; more_data: @@ -347,6 +347,7 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock, tosend = msg->sg.size; if (psock->apply_bytes && psock->apply_bytes < tosend) tosend = psock->apply_bytes; + eval = __SK_NONE; switch (psock->eval) { case __SK_PASS: