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 8287C3B2AA for ; Sat, 8 Aug 2026 12:05:48 +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=1786190749; cv=none; b=LLrCdcoAL3yXbZD3s2yD/QRCKNOeoVhoqi5sFnGXsoSLX+872zX8tHxL0MNHcbQ37X+QI7Gh80fLx+8oZBgBoj5gqn2pTSX8t86A8xDYGQe0CgI2bl5SnfVBkJLeiuYSvdwGBj5fzOFXlmDHsY15M4QUsqJRi6rFLykO/oZee9E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786190749; c=relaxed/simple; bh=Gw70kTeOedPaVNwVvALMqSKf5RTqt5MTFA8rjFtihF4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dZT4whOw+WaWsJfUpapxuDqeTc4tXi1uaiIIg6fzlf4p3agLVZSGQjf99msoEy4kgROdNYJhWZTqYhr7Fk5U96d+Ohe/XyOUnNfveX+a+TIMpc10X5+f4fcLtUwL4z/LBFhrSpAaHyTt4q7h/hIIwNwSU0Nxkddd2lbrdEDrcYc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=d3zsFYAr; 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="d3zsFYAr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 836261F000E9; Sat, 8 Aug 2026 12:05:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786190748; bh=zoL3/U27KlGEaWKSnUf2OJ5Lk0mC0gYYn6E7oXrjnxk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=d3zsFYAr/7+egESSgd9M3oA7kbyZXfhVtRGzAwrCLExilE8Knoli2WudIf0GB6qM2 6IkjzSpSg2YSX4mbZVNCUJaOBxrZH2MG7dzj+r1U3iA+4sZaEoFON0Y+5bv2HzFZPF +PGFY0oqXA7vwqo7HTt05av9ZB8N/qvSwJmRt/NhC156CU+W35ihVXUR6D1X6waqKN qEWQ+vBx0mW3s5+0pjVC0PDMmKh9gsMoKrfT0pxS4kXTLDqA1z4hCTAyJWCbcapbrk XD1Qnrvh4caMkFWnMOj0F3oLcU/OC94lqeRZgDpjXXhpwcdwIldeMypyjEuWZD2hEx bJl1ngt1tWX2g== From: Sasha Levin To: stable@vger.kernel.org Cc: Pavitra Jha , Viacheslav Dubeyko , Ilya Dryomov , Sasha Levin Subject: [PATCH 5.10.y] libceph: fix two unsafe bare decodes in decode_lockers() Date: Sat, 8 Aug 2026 08:05:45 -0400 Message-ID: <20260808120545.220270-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026072949-fresh-evolution-3660@gregkh> References: <2026072949-fresh-evolution-3660@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 a109a556115271ca7896dcda7b4b7e45e156c227 ] decode_lockers() in cls_lock_client.c contains two bare decode operations that allow a malicious or compromised OSD to trigger slab-out-of-bounds reads: 1. ceph_decode_32(p) at the num_lockers field has no preceding bounds check. ceph_start_decoding() accepts struct_len=0 as valid -- the internal ceph_decode_need(p, end, 0, bad) always passes -- so when an OSD sends struct_len=0, ceph_start_decoding() returns success with p == end. The immediately following bare ceph_decode_32(p) then reads 4 bytes past the validated buffer boundary. The garbage value is passed directly to kzalloc_objs() as the locker count. The sibling function decode_watchers() in osd_client.c already uses ceph_decode_32_safe() after its own ceph_start_decoding() call. decode_lockers() was the only site using the bare variant. 2. ceph_decode_8(p) after the decode_locker() loop has no preceding bounds check. If an OSD crafts num_lockers such that the loop advances p exactly to end, the subsequent bare ceph_decode_8(p) reads one byte past the validated buffer boundary. The result is passed directly into *type, which is used as a lock type discriminator by callers, giving an OSD-controlled one-byte OOB read with direct influence over the lock type field. Fix both by replacing bare operations with their safe variants: ceph_decode_32(p) -> ceph_decode_32_safe(p, end, *num_lockers, err_inval) ceph_decode_8(p) -> ceph_decode_8_safe(p, end, *type, err_free_lockers) The goto targets differ intentionally: err_inval: is a new label returning -EINVAL directly. It is used for the pre-allocation failure path where *lockers is not yet allocated and must not be passed to ceph_free_lockers(). err_free_lockers: is the existing label. It is used for the post-allocation failure path where *lockers is allocated and must be freed. ret is set to -EINVAL before ceph_decode_8_safe() so that err_free_lockers returns the correct error code on bounds violation. Without this, err_free_lockers would return a stale ret value (0 from the successful decode_locker() loop), silently swallowing the error. -EINVAL is correct for both failure paths. The data received from the OSD is structurally malformed. -ENOMEM would misrepresent the failure class to callers and to stable@ backporters triaging error paths. Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment can trigger this against any kernel client that issues the lock.get_info class method (e.g. during RBD exclusive lock acquisition). [ idryomov: trim changelog, formatting ] Cc: stable@vger.kernel.org Fixes: d4ed4a530562 ("libceph: support for lock.lock_info") Signed-off-by: Pavitra Jha Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin --- net/ceph/cls_lock_client.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/net/ceph/cls_lock_client.c b/net/ceph/cls_lock_client.c index 17447c19d9376..fd39cbda60f65 100644 --- a/net/ceph/cls_lock_client.c +++ b/net/ceph/cls_lock_client.c @@ -293,7 +293,7 @@ static int decode_lockers(void **p, void *end, u8 *type, char **tag, if (ret) return ret; - *num_lockers = ceph_decode_32(p); + ceph_decode_32_safe(p, end, *num_lockers, err_inval); *lockers = kcalloc(*num_lockers, sizeof(**lockers), GFP_NOIO); if (!*lockers) return -ENOMEM; @@ -304,7 +304,8 @@ static int decode_lockers(void **p, void *end, u8 *type, char **tag, goto err_free_lockers; } - *type = ceph_decode_8(p); + ret = -EINVAL; + ceph_decode_8_safe(p, end, *type, err_free_lockers); s = ceph_extract_encoded_string(p, end, NULL, GFP_NOIO); if (IS_ERR(s)) { ret = PTR_ERR(s); @@ -314,6 +315,9 @@ static int decode_lockers(void **p, void *end, u8 *type, char **tag, *tag = s; return 0; +err_inval: + return -EINVAL; + err_free_lockers: ceph_free_lockers(*lockers, *num_lockers); return ret; -- 2.53.0