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 D92B32701B6; Thu, 20 Aug 2026 17:30:23 +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=1787247025; cv=none; b=SYHEoE/8F+Ya74UaFhH8mKcj6uitl7pqDMoY8ZfvuYCyDCF9LTQaG54C6xF5QEH0+ZyCVbZHDp2Mv1h27UHWehkVFG0yx/MgZJVywXIsCOrpIseoeU1rs6o4muGXfkprclCoGY52IdMpNiSxhNIeshSpMy4ijTTEyGaNk5pKT3E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787247025; c=relaxed/simple; bh=tLAIttSxcYca6woVXN15hYwAJF4ZLWKQHNJWht97X8g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uKbSfViHURiZg4Rk/7+33mDJnndHyl9xQb6fVKs50h+ZNfTSAd1awfLs4sZRFkIktfGyzMNhN3sWV0phJzOFWJ5RrjXZDbosWm8VWAbc4zJ3a7WwzskT2YHuYgO7x+vDFQUkEr5J2pyLo9yvf68e1+ozY74hiRBdQ9gFVar5rvw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=B9qlO80T; 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="B9qlO80T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4337A1F000E9; Thu, 20 Aug 2026 17:30:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787247023; bh=/fRh3UCmhQsZFC9kLXNNqVa3CSh9HURl2UO2IACGUAM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=B9qlO80T22eAHDmkbR7Qx9SsMI/T0E+Ss76BgPxqUx6mLlQ7Dj0tdIIvH+ajK574l IOVQ24dnNkmn4inx5zu47y3Iakd1+4xmTF5PN6CUClw6gMKHOeQkkTz6a2WwY36918 3o92hR8ZQVkwAhO66LoN/meWhRCB15HIyG/Npw/U= 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 6.12 122/220] libceph: fix two unsafe bare decodes in decode_lockers() Date: Thu, 20 Aug 2026 16:55:12 +0200 Message-ID: <20260820145227.141333772@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145223.480031205@linuxfoundation.org> References: <20260820145223.480031205@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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ 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 Signed-off-by: Greg Kroah-Hartman --- net/ceph/cls_lock_client.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/net/ceph/cls_lock_client.c +++ b/net/ceph/cls_lock_client.c @@ -304,7 +304,7 @@ static int decode_lockers(void **p, void 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; @@ -315,7 +315,8 @@ static int decode_lockers(void **p, void 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); @@ -325,6 +326,9 @@ static int decode_lockers(void **p, void *tag = s; return 0; +err_inval: + return -EINVAL; + err_free_lockers: ceph_free_lockers(*lockers, *num_lockers); return ret;