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 5F094439F86 for ; Mon, 24 Aug 2026 15:34:40 +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=1787585681; cv=none; b=BX/2bmioyZvx7G6sbABCnPe5Y4e5CiGYdBVKGmZrnohd7utf45UkSsloSbohrZO75A0VGYtYeHW1YV/PwlAJjSJJUGYdOseqTYIY9WMiCNDIbma6ZSCZN82x6xmV9PjanLaB35UeBY9kQvvd92351Iqbw+4/9IrjN0uK8THUKqg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787585681; c=relaxed/simple; bh=LD25mc55Ci+THDGXv4PexIzjSt2pjtJ6qoO5lPi185g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iFcukRUycnTKLlbE1rjDzniH8tuVmXRkf/3KcfXMnQVZMdZX3+fr2E113tTcnbIGJGkZ8xy7GgAssm0hMkBhrVdMz8gQPgivNF/4QBxMhL/2BCtoBDRNmUYv1vL0Mc5OEsz+mqZ2u/tv219K/tDRP4Ctsx7IFd3NAOT+EMrXOu0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XdXQldvq; 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="XdXQldvq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5C5E51F00A3A; Mon, 24 Aug 2026 15:34:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787585680; bh=o4rUx+0dZN+7k0+rvVGxygzDDmZK1/jzP1bvurs4aXg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=XdXQldvqVcvEHWFrsDB4oIQeo1ha0hreRFrzcNuihugSjQcxpliwzozuo6GSRjmLg +wN2ZjLoUBx0NPxcv/mtjSsYTCTF2HAOuaj6m11x/LfUdOwUOuEri+5iN0syyTf4ZA f98Ig32t1tQjpchfpWC2ytbYHJLD+GAkph3LWnncrRhnqFXAyENRwAkmvI9MfxL3NI +4TWwlBW5n+O4HCN17ZJcWuzT3q83LgzsV4sYGWk9jAKD3XF0v29fX7Lfa6HOXiUsh FEuLlrf9EAoEOG9o4rhVqM7R59XXnvXpEukvDr7cCZG0i10FKfI3Bw21w+R7njNweH RWp9LdfF9Ifig== From: Sasha Levin To: stable@vger.kernel.org Cc: Pavitra Jha , Viacheslav Dubeyko , Ilya Dryomov , Sasha Levin Subject: [PATCH 5.10.y] libceph: fix OOB read in decode_watchers() via missing bounds check Date: Mon, 24 Aug 2026 11:34:37 -0400 Message-ID: <20260824153437.3851112-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026082058-swiftly-hardwood-656a@gregkh> References: <2026082058-swiftly-hardwood-656a@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 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 89b02b8baca35..92d379c60da5c 100644 --- a/net/ceph/osd_client.c +++ b/net/ceph/osd_client.c @@ -4993,7 +4993,7 @@ 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; @@ -5007,6 +5007,9 @@ static int decode_watchers(void **p, void *end, } return 0; + +bad: + return -EINVAL; } /* -- 2.53.0