From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-182.mta0.migadu.com (out-182.mta0.migadu.com [91.218.175.182]) (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 002202F28FC for ; Thu, 11 Jun 2026 12:39:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781181553; cv=none; b=tcQeiR4pqCFuEVoisOTsy8vn45anO5EeV3HYcEmksfLzPTr4u9CA6lkMUVoJvVq0BKoCoJjG4155VBMARGc7rzABenetL+5SnVdu+KB1/8kuAmf/+t1pyyAHhyN7gOEzcRdP8ZwOlg6/aWiHkcKAuV1pABulxh0w73IR3DoVJgw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781181553; c=relaxed/simple; bh=c2g8WkNZdy9SmxdKoIzElNcy39kSDQgaBCXoxEeNlN4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LNPMwA6p8CJhO7QD3CxQd45RYJbmVR1o8PiYY1Mc/bW2hWs+0cvyOCbw/W63YnyLOocal025oktknATRLbyYf0vC54bpVFCzuvaoTj+DKQIUWYvlj7vGULNfQ3Q7GwSF1dwYHsWwPz47hctxa7bjpdT5ibf3goqbhmwCiocgXvI= 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=I144PC0u; arc=none smtp.client-ip=91.218.175.182 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="I144PC0u" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1781181549; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=htxaBRqgJJwIgSGsPQlozFytcsGKySwMz0N5LwBygaI=; b=I144PC0u/OG52044NrqyKOQ2uxXsP3BaHF9MuGxxfNcDSkfdbY9Q8cZRxpDx4zwTegF9gz kMwFLeiL2qmC9p/3DTnryNbKZAfKIHtGbPm0LmqpBjfqx6FirBchb7WXgII7hnPw7MhRyj 9fh4YSGl7RwwTvTasJYE1cJWf2M0Q2g= From: Jiayuan Chen To: bpf@vger.kernel.org Cc: Sechang Lim , Jiayuan Chen , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , John Fastabend , Stanislav Fomichev , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Jakub Sitnicki , Shuah Khan , Jesper Dangaard Brouer , Ihor Solodrai , Cong Wang , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf v2 6/7] bpf, sockmap: fix integer overflow in bpf_msg_pop_data() bounds check Date: Thu, 11 Jun 2026 20:34:14 +0800 Message-ID: <20260611123538.156005-7-jiayuan.chen@linux.dev> In-Reply-To: <20260611123538.156005-1-jiayuan.chen@linux.dev> References: <20260611123538.156005-1-jiayuan.chen@linux.dev> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: Sechang Lim start and len are u32, so u64 last = start + len; evaluates start + len in 32-bit and wraps before storing it in last. The bounds check if (start >= offset + l || last > msg->sg.size) return -EINVAL; can then be passed with an out-of-range start/len, after which the pop loop runs off the end of the scatterlist and sk_msg_shift_left() calls put_page() on the empty msg->sg.end slot: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] RIP: 0010:sk_msg_shift_left net/core/filter.c:2957 [inline] RIP: 0010:____bpf_msg_pop_data net/core/filter.c:3103 [inline] RIP: 0010:bpf_msg_pop_data+0x753/0x1a10 net/core/filter.c:2984 Call Trace: bpf_prog_4cc92c278f4d5d56+0x1b1/0x1e8 bpf_prog_run_pin_on_cpu+0x107/0x320 include/linux/filter.h:746 sk_psock_msg_verdict+0x357/0x7f0 net/core/skmsg.c:934 tcp_bpf_send_verdict net/ipv4/tcp_bpf.c:420 [inline] tcp_bpf_sendmsg+0x766/0x1ae0 net/ipv4/tcp_bpf.c:583 __sock_sendmsg+0x153/0x1c0 net/socket.c:802 __sys_sendto+0x326/0x430 net/socket.c:2265 __x64_sys_sendto+0xe3/0x100 net/socket.c:2268 do_syscall_64+0x14c/0x480 entry_SYSCALL_64_after_hwframe+0x77/0x7f Widen the addition with a (u64) cast so the bound is evaluated in 64-bit and a len near U32_MAX no longer wraps below msg->sg.size. While here, change pop from int to u32. It counts bytes against the unsigned scatterlist lengths and can never be negative, so the signed type only invites sign-confusion in the pop loop. Fixes: 7246d8ed4dcc ("bpf: helper to pop data from messages") Reviewed-by: Jiayuan Chen Signed-off-by: Sechang Lim --- net/core/filter.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index e35e681a15dca..742aeeea13c26 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3048,8 +3048,8 @@ BPF_CALL_4(bpf_msg_pop_data, struct sk_msg *, msg, u32, start, u32, len, u64, flags) { u32 i = 0, l = 0, space, offset = 0; - u64 last = start + len; - int pop; + u64 last = (u64)start + len; + u32 pop; if (unlikely(flags)) return -EINVAL; -- 2.43.0