From nobody Fri Sep 25 12:00:48 2026 Received: from mail-pj2-f13.google.com (mail-pj2-f13.google.com [74.125.227.141]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 852AF2F260C for ; Sat, 12 Sep 2026 21:54:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.227.141 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789250047; cv=none; b=m9y+McJs/wGP9pI1f/wcEe40XXFB125AffXU6r7PSYRDumMZDP1PylsQqTYYG+oLwAaeWNl1bswmz/LTuM9o4oG2cpNGBRyrLql8UlGrl1oaa/4oR8Cul+ABw4Yf7+i4t9xwNMW16Pu8LtXptw2f3nWL1viiV+r96/HUIwnNX/0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789250047; c=relaxed/simple; bh=2w2Xokvxv3Zza1WDoW8p2uRdZXNP1otSV6DskpOG3dI=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=d2dQOwh5NpitVWueC20JY1pj5qAZ2BvHkNGOYv5sply2DQwdFGDhMJK4A7nq49QsH2xTIdBbwq4WHrJ7OqDcEgPKdRyJfzwWLarRJw7hDgpcqPor0e91qAq4/tAHTElRvwFw+bj/lRoy4cLUnjE2VoS3uSYLjxCX7ZSgQrD1fYI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=asu.edu; spf=pass smtp.mailfrom=asu.edu; dkim=pass (2048-bit key) header.d=asu.edu header.i=@asu.edu header.b=DdKdcAs4; arc=none smtp.client-ip=74.125.227.141 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=asu.edu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=asu.edu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=asu.edu header.i=@asu.edu header.b="DdKdcAs4" Received: by mail-pj2-f13.google.com with SMTP id d9443c01a7336-2d747eb79fbso4992025ad.3 for ; Sat, 12 Sep 2026 14:54:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=asu.edu; s=google; t=1789250045; x=1789854845; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=LExfl2fEFs87Gnc/CJkjB7Li4LuphLalhWsojqEvmUw=; b=DdKdcAs4Mkks026c4JirbiMixV+VsGamJLs0A3tnPo8pyDznWN6I8epdMOHy2xRDIe I8u13BrmTf4HnT13J8EmO/5+eiRiiHDHzdhjpCVgfFykDGDPD0PEJ+ncX1VMGG9ZQXFA UyipmaCrHpK4St1rYih95O5EOgNjRjaZmgOyp4/2WtGfKJ5vqPWThpztHdsBgLz4rUa8 xyKw1cvR3rufdAaUFNmjYDnxMcX+TqMURtLTMMudPm2uby5+4cSMPC7T727SJUZrNRwy EaUfge23gyjPo00VpGQ2a4CW/71LWMw5bYrHCcodVvx6toH52YNF0PLaHFg4J/CIx+aZ MNgA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1789250045; x=1789854845; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=LExfl2fEFs87Gnc/CJkjB7Li4LuphLalhWsojqEvmUw=; b=QJJ6VjJ0LNpTwhss841WycaOz7tlSeZzQd/vJQyu/8tzMsnelfbNN4JewFymU4eetE 4j88gHYlGuOFzanqnawHZ7HzXC3ygynJrEmY3Bs+EpZDmzbFDTNx53rFahXBwrmH/Ufr 7oQfdbOjsQt9Lmmepim+57oF34gBCPI3Z0Nluw2+SufuOUIutKv5eEQtMG7NP9w6xKWR r2Lco8Qa7RI5cE33b2NV8UqEbkPjRWckDkRiB/HvE2Lh9snENubHSF5gba1h9gy/tYFy mSMfsivi5PG8IzUt03HLnxXM5XoHrUgmJQC0Ppsh4qciGsP8e5tlPYHxVcil3ZP+jaOS Myhw== X-Forwarded-Encrypted: i=1; AKwUvBzGGJ95ptp/7J5kCQxbbB4/fHGcCIc+D6NAcXGcAtEG4qrcduV50P6h/yXjTiqap1KIX0/LPqGh3dhhbww=@vger.kernel.org X-Gm-Message-State: AFuF++lAKVWIfdI5FbHo7K+mkZJItBWbtBq/fZyL83cAXVPLaLmJrQhm GvzD3L4bVWpgxwg4eGXeSRMMeH987K519IIdjTXczHTybrvj5yiPfrZEOrDwClj2uw== X-Gm-Gg: AYBFou1+NFj7vw6jP7wb4YdeKh5FOxquIKIwwaaeaKu45vQ+CLyZBzS/46zgiNDc8um mwtduzJ3HPZHQnfQMUsO7K4HQjnNvvGQUD0bo5rpcLN8ElaIs65SzHFKkcLh2njYDBFwgQlXFHc /YKCgaGjASyx0LO4foWJyab5N46gKmckWT9kNFmMlY6PJ32aoYMJ8qJR6ghjyMsu262VUaF4RIi yoP5TYX7r5+xFolebpV4N7CCLo6NOn+xmHVHCy20IIul/ZOG8XtnypS2rNHIALa+d0wf23IhL4q RPKw4+GXMHTpAczldQYkoCv+9PxUuMcNnSsSC+7ANT5bb/p+3NEBFy9YcTzGbO+/LyXgz71+zyl eYfwJDMqJVdVyqRZrBvFA/kvnCdeXsjAp1rQ57fmV5Y8J86UAplWqF9e/C4TpPa2ZvCBqvh1DG5 k3Yqo/k6Z1IRf5iK99FExoxigSXriGqPuMMwR/WKCmyKp77RjrFpP8+HdAHGBOJG6LEFF6EiFxx lUWnGRt4PsKGbIhbrNT8VOfYiGABcQS2PXLqhRzzRZQ5tXOSbPis6Lw X-Received: by 2002:a17:903:19cf:b0:2c9:e9db:8167 with SMTP id d9443c01a7336-2dd2a1ea679mr208126375ad.7.1789250044780; Sat, 12 Sep 2026 14:54:04 -0700 (PDT) Received: from xps.tailc0aff1.ts.net (149-169-99-5.nat.asu.edu. [149.169.99.5]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-33ba4efc398sm18474475eec.19.2026.09.12.14.54.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 12 Sep 2026 14:54:04 -0700 (PDT) From: Xiang Mei To: mst@redhat.com, jasowangio@gmail.com, eperezma@redhat.com, xuanzhuo@linux.alibaba.com Cc: virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, co+6dcbccedc9ec6452@bugs.sh, Xiang Mei Subject: [PATCH] vdpa: fix double free of the reply skb in vdpa_nl_cmd_dev_config_get_doit() Date: Sat, 12 Sep 2026 14:54:01 -0700 Message-ID: <20260912215401.126194-1-xmei5@asu.edu> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" genlmsg_reply() consumes the reply skb on every outcome: netlink_unicast() frees it whether it queues it, drops it, or bails out early. vdpa_nl_cmd_dev_config_get_doit() lets its return value fall through to the shared error label, which calls nlmsg_free(msg) again and double-frees the sk_buff on any reply failure. The failure is reachable unprivileged: VDPA_CMD_DEV_CONFIG_GET carries no GENL_ADMIN_PERM, so batching several requests into one sendto() on a socket with a shrunken SO_RCVBUF fills the receive queue, and netlink_attachskb() then takes its MSG_DONTWAIT path, freeing the skb and returning -EAGAIN. Set msg to NULL once genlmsg_reply() has consumed it so the shared exit path frees the skb only on the early error gotos that still own it; nlmsg_free(NULL) is a no-op. BUG: KASAN: slab-use-after-free in sk_skb_reason_drop (net/core/skbuff.c:= 1220) Read of size 4 at addr ffff88800d99d49c by task exploit/147 Call Trace: sk_skb_reason_drop (net/core/skbuff.c:1220) vdpa_nl_cmd_dev_config_get_doit (drivers/vdpa/vdpa.c:1324) genl_family_rcv_msg_doit (net/netlink/genetlink.c:1114) genl_rcv_msg (net/netlink/genetlink.c:1194) netlink_rcv_skb (net/netlink/af_netlink.c:2556) genl_rcv (net/netlink/genetlink.c:1218) netlink_unicast (net/netlink/af_netlink.c:1345) netlink_sendmsg (net/netlink/af_netlink.c:1900) __sys_sendto (net/socket.c:2281) __x64_sys_sendto (net/socket.c:2284) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) The buggy address belongs to the object at ffff88800d99d3c0 which belongs to the cache skbuff_head_cache of size 232 The buggy address is located 220 bytes inside of freed 232-byte region [ffff88800d99d3c0, ffff88800d99d4a8) Fixes: ad69dd0bf26b ("vdpa: Introduce query of device config layout") Reported-by: co+6dcbccedc9ec6452@bugs.sh Closes: https://lore.kernel.org/all/ILTHcT8oe1HP47sY25JVxssvKmkCTjYlX9Hs%40= bugs.sh/ Assisted-by: Claude:claude-opus-5 Signed-off-by: Xiang Mei --- drivers/vdpa/vdpa.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c index 47c6c3d23f5c..6455f837dd26 100644 --- a/drivers/vdpa/vdpa.c +++ b/drivers/vdpa/vdpa.c @@ -1313,15 +1313,16 @@ static int vdpa_nl_cmd_dev_config_get_doit(struct s= k_buff *skb, struct genl_info } err =3D vdpa_dev_config_fill(vdev, msg, info->snd_portid, info->snd_seq, 0, info->extack); - if (!err) + if (!err) { err =3D genlmsg_reply(msg, info); + msg =3D NULL; + } =20 mdev_err: put_device(dev); dev_err: up_read(&vdpa_dev_lock); - if (err) - nlmsg_free(msg); + nlmsg_free(msg); return err; } =20 --=20 2.43.0