From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-178.mta0.migadu.com (out-178.mta0.migadu.com [91.218.175.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8953431D39F for ; Wed, 10 Sep 2025 05:15:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.178 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757481347; cv=none; b=EC9M3BxzF2JGkXpoKXi0LwZWa6HQVK9Cd2VN0dOXTu2nx3TvG8a7MgvPjvmvmHyR/0RcrY8k9qssqhH29cmxzLjvhFVDXGqiYQw+EV8pFcSA4bhHOL0LYbS1FjUKmglmDGSyCHRE3vlROZq5zEzUD++0onqcNY/uRdkwBZ1+hZI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757481347; c=relaxed/simple; bh=s3pg7UyNfKWHgmE20zYNwMxjapyp73QbUHBrcGNUhA4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=uUJpXhJAAMsPjRr4Dd1w76/m5+OACYYKSGFvfpkHcy3MxjUV8H+4mZtzHBJpS2gmnFvANZCzmQ+pnzCTEz1G1Hja7FRx0evd95kAiCJLKd6h4zpbWmPCkQ4sF/okyfG6zs/Oo7HRkCzV+EpIRKSGOA8AyYNt0JJUIt0VZWJcipk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=BZ9QXmZJ; arc=none smtp.client-ip=91.218.175.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="BZ9QXmZJ" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1757481342; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=I4kIPGvCkyCNRQ7MQfHXdmZOt8slBwBvSdHTOyW6NXs=; b=BZ9QXmZJxapXz7eXpIQpNic75a15WDzhsNUajPo3VO8oDChcS3baWuPjY9f7bkvoh/88Of 7T7wHuOdZVZNNno1cH/gVXDF9Ji/hId6Iomxw0jS6WwEvTLUImuYU/l8rya7HeDWAhNnI1 FXvmmpnmx8hPrSORcUkdyfYvBNB5r94= Date: Tue, 9 Sep 2025 22:15:37 -0700 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v1 bpf] tcp_bpf: Call sk_msg_free() when tcp_bpf_send_verdict() fails to allocate psock->cork. To: Kuniyuki Iwashima Cc: John Fastabend , Jakub Sitnicki , Alexei Starovoitov , Daniel Borkmann , Kuniyuki Iwashima , netdev@vger.kernel.org, bpf@vger.kernel.org, syzbot+4cabd1d2fa917a456db8@syzkaller.appspotmail.com References: <20250909232623.4151337-1-kuniyu@google.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Martin KaFai Lau In-Reply-To: <20250909232623.4151337-1-kuniyu@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 9/9/25 4:26 PM, Kuniyuki Iwashima wrote: > syzbot reported the splat below. [0] > > The repro does the following: > > 1. Load a sk_msg prog that calls bpf_msg_cork_bytes(msg, cork_bytes) > 2. Attach the prog to a SOCKMAP > 3. Add a socket to the SOCKMAP > 4. Activate fault injection > 5. Send data less than cork_bytes > > At 5., the data is carried over to the next sendmsg() as it is > smaller than the cork_bytes specified by bpf_msg_cork_bytes(). > > Then, tcp_bpf_send_verdict() tries to allocate psock->cork to hold > the data, but this fails silently due to fault injection + __GFP_NOWARN. > > If the allocation fails, we need to revert the sk->sk_forward_alloc > change done by sk_msg_alloc(). > > Let's call sk_msg_free() when tcp_bpf_send_verdict fails to allocate > psock->cork. > > [0]: > WARNING: net/ipv4/af_inet.c:156 at inet_sock_destruct+0x623/0x730 net/ipv4/af_inet.c:156, CPU#1: syz-executor/5983 > Modules linked in: > CPU: 1 UID: 0 PID: 5983 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 > RIP: 0010:inet_sock_destruct+0x623/0x730 net/ipv4/af_inet.c:156 > Code: 0f 0b 90 e9 62 fe ff ff e8 7a db b5 f7 90 0f 0b 90 e9 95 fe ff ff e8 6c db b5 f7 90 0f 0b 90 e9 bb fe ff ff e8 5e db b5 f7 90 <0f> 0b 90 e9 e1 fe ff ff 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 9f fc > RSP: 0018:ffffc90000a08b48 EFLAGS: 00010246 > RAX: ffffffff8a09d0b2 RBX: dffffc0000000000 RCX: ffff888024a23c80 > RDX: 0000000000000100 RSI: 0000000000000fff RDI: 0000000000000000 > RBP: 0000000000000fff R08: ffff88807e07c627 R09: 1ffff1100fc0f8c4 > R10: dffffc0000000000 R11: ffffed100fc0f8c5 R12: ffff88807e07c380 > R13: dffffc0000000000 R14: ffff88807e07c60c R15: 1ffff1100fc0f872 > FS: 00005555604c4500(0000) GS:ffff888125af1000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00005555604df5c8 CR3: 0000000032b06000 CR4: 00000000003526f0 > Call Trace: > > __sk_destruct+0x86/0x660 net/core/sock.c:2339 > rcu_do_batch kernel/rcu/tree.c:2605 [inline] > rcu_core+0xca8/0x1770 kernel/rcu/tree.c:2861 > handle_softirqs+0x286/0x870 kernel/softirq.c:579 > __do_softirq kernel/softirq.c:613 [inline] > invoke_softirq kernel/softirq.c:453 [inline] > __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680 > irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 > instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] > sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052 > > > Fixes: 4f738adba30a ("bpf: create tcp_bpf_ulp allowing BPF to monitor socket TX/RX data") > Reported-by: syzbot+4cabd1d2fa917a456db8@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/netdev/68c0b6b5.050a0220.3c6139.0013.GAE@google.com/ > Signed-off-by: Kuniyuki Iwashima > --- > net/ipv4/tcp_bpf.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c > index ba581785adb4..ee6a371e65a4 100644 > --- a/net/ipv4/tcp_bpf.c > +++ b/net/ipv4/tcp_bpf.c > @@ -408,8 +408,10 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock, > if (!psock->cork) { > psock->cork = kzalloc(sizeof(*psock->cork), > GFP_ATOMIC | __GFP_NOWARN); > - if (!psock->cork) > + if (!psock->cork) { > + sk_msg_free(sk, msg); Nothing has been corked yet, does it need to update the "*copied": *copied -= sk_msg_free(sk, msg); > return -ENOMEM; > + } > } > memcpy(psock->cork, msg, sizeof(*msg)); > return 0;