From: Pengcheng Yang yangpc@wangsu.com
[ 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@wangsu.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Jakub Sitnicki jakub@cloudflare.com Link: https://lore.kernel.org/bpf/1669718441-2654-2-git-send-email-yangpc@wangsu.c... Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/tcp_bpf.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index f69dcd3c7797..229fa1f2b381 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -312,7 +312,7 @@ 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: @@ -343,6 +343,7 @@ 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: