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 69C263815CC for ; Sun, 5 Jul 2026 14:13:57 +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=1783260838; cv=none; b=a88Rk+735cTIJdyZn4HnF6moSu5j6b+yCPRD11WuWsMBaO7jSqhYewhKfptYB+o0d9utbiRmNf3rG23WvP0KiZZycXlLUIsttxry/VmkggcMqk/ZM8F0xx8dQtrn8olNlWqmCHRgtMqrVl7nJG32urenfNSByLvp8gYngYSms5Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783260838; c=relaxed/simple; bh=WGKpf2cy+VUICVIGNqCr2JHMS7JYyM0p3lZUY/UUtNM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PW55AxzJt/AcmLTgZvg58KlyYpbxkFhIStLUZegG1COCW4YsJZK0hNgT1/MneNvJHR8JW22fsfsJ/Yybv+khPKQL4TsUtnPqc18o+XoAhnLgOOllEEQ/mms+BzjNaHlcThZQwBF5odeCHcK+YmkQJQ6g4MpkcfVFNiqnzR6oSzc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QigWzLbX; 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="QigWzLbX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7A9981F000E9; Sun, 5 Jul 2026 14:13:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783260837; bh=5I5lei73yaGFMazl+M0cpvM+xK2GWYXQu1ze92QM1U0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=QigWzLbXa4JFlyWYoWMBMZKRISjQ2NZvyfyHfxnzj5t8QrZUJPmHClH1iNCM+yHOP Sax+7PCIrgGVbR6UWsZeSDt7qYSuEmT+maoUe5/kADAuj6cLU5uzgNnwxCs/u5ICvB ORDlLjP/6a7WaYfs5YUsobGPNIKivDbdLdzjDKckF4JqWIqFEF/Jh65c00RsZacyxC 6s+gwhN/cv+/onoLizwjWryVhBx7TNE9RqbPO1uCvjYy3SWXrOegQg+gUnRvY03lEj TLzlyCg5kPReX4706XoNG+Y4e5nUiSTDSL62tE3cvFSNI8LiD0zqWgkBMsRPQymKPG c6aRjfBbuR2TA== From: Sasha Levin To: stable@vger.kernel.org Cc: Michael Bommarito , Anna Schumaker , Sasha Levin Subject: [PATCH 5.15.y] NFSv4/flexfiles: reject zero filehandle version count Date: Sun, 5 Jul 2026 10:13:55 -0400 Message-ID: <20260705141355.1783874-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026070244-vehicular-daintily-d589@gregkh> References: <2026070244-vehicular-daintily-d589@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: Michael Bommarito [ Upstream commit 2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2 ] ff_layout_alloc_lseg() decodes the filehandle-version array count from the flexfiles layout body. The value is used as the count for kzalloc_objs(), and the current code only rejects NULL. A zero count yields ZERO_SIZE_PTR, which can be stored in dss_info->fh_versions even though later flexfiles paths assume that at least one filehandle version exists. Reject fh_count == 0 before the allocation, matching the existing zero version_count validation in the flexfiles GETDEVICEINFO parser. A QEMU/KASAN run with a malformed flexfiles layout hit: KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:ff_layout_encode_ff_layoutupdate.isra.0+0x15f/0x750 ff_layout_encode_layoutreturn+0x683/0x970 nfs4_xdr_enc_layoutreturn+0x278/0x3a0 Kernel panic - not syncing: Fatal exception The patched kernel rejects the malformed layout without KASAN/oops/panic, and a valid fh_count=1 regression still opens, reads, and unmounts cleanly. Cc: stable@vger.kernel.org Fixes: d67ae825a59d ("pnfs/flexfiles: Add the FlexFile Layout Driver") Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Michael Bommarito Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin --- fs/nfs/flexfilelayout/flexfilelayout.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c index 24d97d7ba12d56..8fb5e05c4b266c 100644 --- a/fs/nfs/flexfilelayout/flexfilelayout.c +++ b/fs/nfs/flexfilelayout/flexfilelayout.c @@ -454,6 +454,10 @@ ff_layout_alloc_lseg(struct pnfs_layout_hdr *lh, if (!p) goto out_err_free; fh_count = be32_to_cpup(p); + if (fh_count == 0) { + rc = -EINVAL; + goto out_err_free; + } fls->mirror_array[i]->fh_versions = kcalloc(fh_count, sizeof(struct nfs_fh), -- 2.53.0