From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 3407E47143A; Tue, 25 Aug 2026 13:40:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787665260; cv=none; b=GFU3E61433LW8A2boi3x9lkuqrCWhdjYl/QgTTRyGwflax4jdXpza+kBWpCmX31MWF73Mj3zrYoB7zhgvQgEyLX1H6lXkRaXuvBtx0sa3E2hsolFc8/bTPBfr7uXY/UBGzhBoqqXV7TmO/aN0saeUjYZXtNE0EqWnl+0IdG4h+4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787665260; c=relaxed/simple; bh=sNJgkObCSGR0IsPxHtg5f0B0g6HCj2TTuzSwuvswPog=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=j9CfnetTI40lF4BXG6fCQRcwtgDiU223zm0FB3bXrHhDFJxEp5V+A2A4F3LljgIAvdLgplPbCiEupaQgivBxVxCDJ5bs2UeGdvrvTXcxXbzek+XJhj5N4f6zia1vxgNy88+KbSha9GConetc7yLcjDcj8tfufUZgfLY156qLjfs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WHDByRER; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="WHDByRER" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 803041F000E9; Tue, 25 Aug 2026 13:40:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787665259; bh=ufHpXA7wbnaxOfhHehh81ARDNpYX6W/E27ljpMQ5KQo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=WHDByRERGCaHzdH8d+euGs0Ilqnzi5LG7ZnGkTsci0cHiwxow1RGwMIc6TDkUaPRj uYuMp41L9EhKT48vLplp7gYqyb+Rht7I3jUz13C0wvK0OEysCg333AtcY+Ae9Etrrh 6s7U5AQk58cUIRMptmqkxXkuFjoxCjaPoIx1FANc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Pavitra Jha , Viacheslav Dubeyko , Ilya Dryomov , Sasha Levin Subject: [PATCH 6.18 33/94] libceph: fix OOB read in decode_watchers() via missing bounds check Date: Tue, 25 Aug 2026 15:25:29 +0200 Message-ID: <20260825132543.209854180@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260825132541.887883084@linuxfoundation.org> References: <20260825132541.887883084@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pavitra Jha [ Upstream commit 00ead17c7de137a692edee59f2772e6af687e8eb ] ceph_start_decoding() validates that struct_len bytes remain in the buffer after the encoding header, but accepts struct_len=0 as valid: ceph_decode_need(p, end, 0, bad) always passes. When a malicious or compromised OSD sends an obj_list_watch_response_t reply with struct_len=0, ceph_start_decoding() returns success with p == end, leaving zero bytes guaranteed for subsequent reads. The immediately following ceph_decode_32(p) in decode_watchers() has no preceding bounds check. With p == end this is a 4-byte read past the validated buffer boundary. The garbage value is then passed directly to kzalloc_objs() as the watcher count. The sibling function decode_watcher() already uses the safe variants (ceph_decode_copy_safe, ceph_decode_64_safe, ceph_decode_skip_32) after its own ceph_start_decoding() call. decode_watchers() is the only site that uses the bare variant, confirming an oversight. Fix by replacing ceph_decode_32(p) with ceph_decode_32_safe(p, end, *num_watchers, bad), consistent with the established pattern. Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment (e.g. cloud) can trigger this against any kernel client that calls CEPH_OSD_OP_LIST_WATCHERS, without any further privileges beyond OSD session establishment. [ idryomov: trim changelog ] Cc: stable@vger.kernel.org Fixes: a4ed38d7a180 ("libceph: support for CEPH_OSD_OP_LIST_WATCHERS") Signed-off-by: Pavitra Jha Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov [ kept the tree's `kcalloc()` context line instead of upstream's `kzalloc_objs()` ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/ceph/osd_client.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/net/ceph/osd_client.c +++ b/net/ceph/osd_client.c @@ -5033,7 +5033,7 @@ static int decode_watchers(void **p, voi if (ret) return ret; - *num_watchers = ceph_decode_32(p); + ceph_decode_32_safe(p, end, *num_watchers, bad); *watchers = kcalloc(*num_watchers, sizeof(**watchers), GFP_NOIO); if (!*watchers) return -ENOMEM; @@ -5047,6 +5047,9 @@ static int decode_watchers(void **p, voi } return 0; + +bad: + return -EINVAL; } /*