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 726ED175A88 for ; Sat, 8 Aug 2026 11:55:15 +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=1786190116; cv=none; b=ToXCwbB/IeNZ+rLyDYLHMzVgEJnCrlJLCBCuRxs0B2WSJ8EnEDeQ/Sn2oGu+dataAVFUm35mKwNnuBarssCFvMH5sFGJDGquMIHK6cbsJlimxrEQSucHs+5gOCm1ChYFiVR/UeJBlWgzg6j6juvJ6JFnEF/huPVGjAUwiBZ3xV8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786190116; c=relaxed/simple; bh=IyrLD+xOFGegidxPyTKb2SJKhYGf8XZnAXwmn3D7l4o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Wt/Yh43y6HorT02OdSij1Rk2emMz3ZTsZhrXuEY7tMQEBOqKg5/Sq0WDy0VZ8RcIUIkxtxzshuxoaVU/i6Aafxk1CK6TPBSoAIU+ZsVLcM1q14EbqXrIvGg23Gg3E6n0ZyY6jECbV7O9sjTvMZ4hWIz3Nm2Vgk764iYofKj8SeM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BjzsHcrO; 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="BjzsHcrO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6BE001F000E9; Sat, 8 Aug 2026 11:55:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786190115; bh=92AbvF1fdfv5VQPfXd7FU6e6xgX6YeJMiU0+N3WLGRI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=BjzsHcrO+k0q6jvxnmrxA36pFiG2OAv66Dq1Li4Jrxl0Go8P2lLx5eaAYuj5VqRCd iMqmJOgpXeNgrq/JQO/cx3HVXIpkG3Jy3ZOd1P89QYPoFFSdxgG9pGvtoWaaGc4OE3 xB0ROgooGwkPJg5iBW6wBcnHnM19kt0gDy575AMG4P4s4aiBL/b/DJHKahA80i9OE5 awK9CKytsH8EMbgjK/TFyiLS2u4RmcHQwjdk5kn5A0/+r2NvRKnKw2eRcIo8Q78wNE ZqDCFPvQyHZneVBL1Spi/v8dlROzlCdlVV6ppUaL3IEzfgzWdcW6OxrIe+0iRtW0Ll 98iR6EQrY5Bdw== From: Sasha Levin To: stable@vger.kernel.org Cc: Pavitra Jha , Viacheslav Dubeyko , Ilya Dryomov , Sasha Levin Subject: [PATCH 6.1.y] libceph: fix two unsafe bare decodes in decode_lockers() Date: Sat, 8 Aug 2026 07:55:12 -0400 Message-ID: <20260808115512.197333-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026072948-wrongdoer-gift-5733@gregkh> References: <2026072948-wrongdoer-gift-5733@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 66136a4c1ce7f..639793597b76c 100644 --- a/net/ceph/cls_lock_client.c +++ b/net/ceph/cls_lock_client.c @@ -299,7 +299,7 @@ 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; @@ -310,7 +310,8 @@ 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); @@ -320,6 +321,9 @@ 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