5.4-stable review patch. If anyone has any objections, please let me know.
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From: Cong Wang cong.wang@bytedance.com
[ Upstream commit fe1910f9337bd46a9343967b547ccab26b4b2c6e ]
When we cork messages in psock->cork, the last message triggers the flushing will result in sending a sk_msg larger than the current message size. In this case, in tcp_bpf_send_verdict(), 'copied' becomes negative at least in the following case:
468 case __SK_DROP: 469 default: 470 sk_msg_free_partial(sk, msg, tosend); 471 sk_msg_apply_bytes(psock, tosend); 472 *copied -= (tosend + delta); // <==== HERE 473 return -EACCES;
Therefore, it could lead to the following BUG with a proper value of 'copied' (thanks to syzbot). We should not use negative 'copied' as a return value here.
------------[ cut here ]------------ kernel BUG at net/socket.c:733! Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP Modules linked in: CPU: 0 UID: 0 PID: 3265 Comm: syz-executor510 Not tainted 6.11.0-rc3-syzkaller-00060-gd07b43284ab3 #0 Hardware name: linux,dummy-virt (DT) pstate: 61400009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) pc : sock_sendmsg_nosec net/socket.c:733 [inline] pc : sock_sendmsg_nosec net/socket.c:728 [inline] pc : __sock_sendmsg+0x5c/0x60 net/socket.c:745 lr : sock_sendmsg_nosec net/socket.c:730 [inline] lr : __sock_sendmsg+0x54/0x60 net/socket.c:745 sp : ffff800088ea3b30 x29: ffff800088ea3b30 x28: fbf00000062bc900 x27: 0000000000000000 x26: ffff800088ea3bc0 x25: ffff800088ea3bc0 x24: 0000000000000000 x23: f9f00000048dc000 x22: 0000000000000000 x21: ffff800088ea3d90 x20: f9f00000048dc000 x19: ffff800088ea3d90 x18: 0000000000000001 x17: 0000000000000000 x16: 0000000000000000 x15: 000000002002ffaf x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: ffff8000815849c0 x9 : ffff8000815b49c0 x8 : 0000000000000000 x7 : 000000000000003f x6 : 0000000000000000 x5 : 00000000000007e0 x4 : fff07ffffd239000 x3 : fbf00000062bc900 x2 : 0000000000000000 x1 : 0000000000000000 x0 : 00000000fffffdef Call trace: sock_sendmsg_nosec net/socket.c:733 [inline] __sock_sendmsg+0x5c/0x60 net/socket.c:745 ____sys_sendmsg+0x274/0x2ac net/socket.c:2597 ___sys_sendmsg+0xac/0x100 net/socket.c:2651 __sys_sendmsg+0x84/0xe0 net/socket.c:2680 __do_sys_sendmsg net/socket.c:2689 [inline] __se_sys_sendmsg net/socket.c:2687 [inline] __arm64_sys_sendmsg+0x24/0x30 net/socket.c:2687 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x48/0x110 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0x40/0xe0 arch/arm64/kernel/syscall.c:132 do_el0_svc+0x1c/0x28 arch/arm64/kernel/syscall.c:151 el0_svc+0x34/0xec arch/arm64/kernel/entry-common.c:712 el0t_64_sync_handler+0x100/0x12c arch/arm64/kernel/entry-common.c:730 el0t_64_sync+0x19c/0x1a0 arch/arm64/kernel/entry.S:598 Code: f9404463 d63f0060 3108441f 54fffe81 (d4210000) ---[ end trace 0000000000000000 ]---
Fixes: 4f738adba30a ("bpf: create tcp_bpf_ulp allowing BPF to monitor socket TX/RX data") Reported-by: syzbot+58c03971700330ce14d8@syzkaller.appspotmail.com Cc: Jakub Sitnicki jakub@cloudflare.com Signed-off-by: Cong Wang cong.wang@bytedance.com Reviewed-by: John Fastabend john.fastabend@gmail.com Acked-by: Martin KaFai Lau martin.lau@kernel.org Link: https://patch.msgid.link/20240821030744.320934-1-xiyou.wangcong@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/tcp_bpf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index 7adefee59cef..6736d0e6b1c6 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -506,7 +506,7 @@ static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size) err = sk_stream_error(sk, msg->msg_flags, err); release_sock(sk); sk_psock_put(sk, psock); - return copied ? copied : err; + return copied > 0 ? copied : err; }
static int tcp_bpf_sendpage(struct sock *sk, struct page *page, int offset,