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 B61FB435AAB for ; Mon, 24 Aug 2026 14:05:59 +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=1787580360; cv=none; b=nUMkIxbCwhYHtu/CWHEqvDKD0ZSqbuJ627awk2vzOBKKgFUJOdB9aKkY8LKHLkzWQi03WB4Jrcm7QPAVmhqzUYBk7pzwyX55fx6Im2Qhre9UzANC+4W0tMENynMR0tFRpB442lRJEwKXY3ZHGYjyGCBagR6GGhO9TDhY7Pc7dOA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787580360; c=relaxed/simple; bh=ojioM/5vcoMdFGYzi5thN3sX1XFzYeVv3UVADOzKXCk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EHIx8wxsn7UiMZm77TG5O2Cz/VsOvV8aeYu712xYTgSHovzHTTlwxO3ahv3VHD1o1a0ESHV9p81QBTxIa4wEQq5x1u7ISmRjpVi99tRqZXKGyseM4brAF/kvJ98MINLMv4emYcbWaALSudfbn2HSdVQOgg5btHN1oFMR9NFKffA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UkCJapoC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UkCJapoC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 14A9F1F000E9; Mon, 24 Aug 2026 14:05:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787580359; bh=dhOjSHkVuzZQCZbeFg1E9dSzdoEEGjgoqbHEo32Tdls=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UkCJapoCAVigiwlOr4X/PTT8GIyUPdV5xsZjQyD1LGBnCipYO/lk+hTrgV9a5ZTV/ 0E5RXfUwC3VNOnmYpyXLy83eUbNk9An/YSH1SDUvktbnRA6pCr8SvDOBVfQ2ADupH0 UCFv/d16DVolWDLhJZqCa6q0SJqe9VjtP7MUU3eq/f1zpS67OCNM8V2T2CTJ8przGQ WzwjNCwF7AtlcUSW/2fF8s6SZaZxjYXLTDwJ4dPkz3F71RLwd1iJlpfqsCI9ffXco/ EOrHqugrioELgwWs54u2rUenqi0I0PjZ6XaQ2l5iAjzC7CyRFK2s5Wk1KRsTflbtLm LepJZd/UeecRQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Pavitra Jha , Viacheslav Dubeyko , Ilya Dryomov , Sasha Levin Subject: [PATCH 6.6.y] libceph: fix OOB read in decode_watchers() via missing bounds check Date: Mon, 24 Aug 2026 10:05:57 -0400 Message-ID: <20260824140557.3098009-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026082056-tingly-moonbeam-e4a0@gregkh> References: <2026082056-tingly-moonbeam-e4a0@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- net/ceph/osd_client.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c index a86ba8b785754..8c1678f10440c 100644 --- a/net/ceph/osd_client.c +++ b/net/ceph/osd_client.c @@ -5090,7 +5090,7 @@ static int decode_watchers(void **p, void *end, 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; @@ -5104,6 +5104,9 @@ static int decode_watchers(void **p, void *end, } return 0; + +bad: + return -EINVAL; } /* -- 2.53.0