From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4F0BB2FC01B for ; Thu, 19 Feb 2026 19:50:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771530623; cv=none; b=Hd/TbedegDHt1WxRULCODWvcZvuTHHBkZOA2maFV4Fe3w/FBdceRHOGTIJvR8KSiNBxhKw3XjQ1HV3+NKCE40ak2LfpzgUkJD7sS5x4VwipcswkAw9UPZN243QrJQCdQ0V6SFKBGfN5guB3oX5OjW5n5cjBudZBvaDbz0nuVSl8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771530623; c=relaxed/simple; bh=5Gw5nAbTft2x9TcdWgtrRybtFUONCCJiImuuk4GOmvM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=hU/rmj8GHXULvifxOIVDwRQubJM1+EDy28PueYHH2KyoRn0OsqDfW6RyOzz/r0nVZWdezV/JFTLWAXtkbuuGBBhCx6r4r66sziEOX8K2strMvA+LT7ky+vDRe7NJD9N7e3kyjqOkTvcvBDNf5hU4OopdVgu3VkkjvuuofNU9Tk4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ce5UiX/r; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ce5UiX/r" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8BF4FC4CEF7; Thu, 19 Feb 2026 19:50:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771530622; bh=5Gw5nAbTft2x9TcdWgtrRybtFUONCCJiImuuk4GOmvM=; h=From:To:Cc:Subject:Date:From; b=ce5UiX/rJoWfjYn+nuo9RUgxoc+ccu/ZuxP093c0zo3tfpCBJzqCaDbtiHrgyBoOX oQ1fSKgVfZRfKGvZs9MWzE2yDGaOB2UA1T2xiXGEIfcOvsXRTwM14g3AXDAUqAfEUP pjXXNDKDFFeOLrQBkh0GFiQafUssNI1YrBMgpPRq/xbedYIvGu2qDf+yXJaEK0hoeu wrb3vBTXVZP1CWG9nWB9QYd5zSVxHWg0E8DWJF6hmUfrW8ctHlyCtFrv5MEs0TWJHv EOcBBUf79fk4QB2jClgTltawdauZWTlB6GFtFOxcLokmeNWvY29YpoJxCBfkMPX5VC 7h5TuAzAFtV5g== From: Jakub Kicinski To: davem@davemloft.net Cc: netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, Jakub Kicinski , leitao@debian.org Subject: [PATCH net] netconsole: avoid OOB reads, msg is not nul-terminated Date: Thu, 19 Feb 2026 11:50:21 -0800 Message-ID: <20260219195021.2099699-1-kuba@kernel.org> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit msg passed to netconsole from the console subsystem is not guaranteed to be nul-terminated. Before recent commit 7eab73b18630 ("netconsole: convert to NBCON console infrastructure") the message would be placed in printk_shared_pbufs, a static global buffer, so KASAN had harder time catching OOB accesses. Now we see: printk: console [netcon_ext0] enabled BUG: KASAN: slab-out-of-bounds in string+0x1f7/0x240 Read of size 1 at addr ffff88813b6d4c00 by task pr/netcon_ext0/594 CPU: 65 UID: 0 PID: 594 Comm: pr/netcon_ext0 Not tainted 6.19.0-11754-g4246fd6547c9 Call Trace: kasan_report+0xe4/0x120 string+0x1f7/0x240 vsnprintf+0x655/0xba0 scnprintf+0xba/0x120 netconsole_write+0x3fe/0xa10 nbcon_emit_next_record+0x46e/0x860 nbcon_kthread_func+0x623/0x750 Allocated by task 1: nbcon_alloc+0x1ea/0x450 register_console+0x26b/0xe10 init_netconsole+0xbb0/0xda0 The buggy address belongs to the object at ffff88813b6d4000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 0 bytes to the right of allocated 3072-byte region [ffff88813b6d4000, ffff88813b6d4c00) Fixes: c62c0a17f9b7 ("netconsole: Append kernel version to message") Signed-off-by: Jakub Kicinski --- CC: leitao@debian.org --- drivers/net/netconsole.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index d144787b2947..1b6a4135ec08 100644 --- a/drivers/net/netconsole.c +++ b/drivers/net/netconsole.c @@ -1679,7 +1679,8 @@ static void send_msg_no_fragmentation(struct netconsole_target *nt, if (release_len) { release = init_utsname()->release; - scnprintf(nt->buf, MAX_PRINT_CHUNK, "%s,%s", release, msg); + scnprintf(nt->buf, MAX_PRINT_CHUNK, "%s,%.*s", release, + msg_len, msg); msg_len += release_len; } else { memcpy(nt->buf, msg, msg_len); -- 2.53.0