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 6438625B09B; Thu, 2 Jul 2026 16:57:29 +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=1783011450; cv=none; b=b7zSXsFKKuMDRjiZQaPNDPEFva2GBszSJiRh1TscA/yCO6ysSPBgqjcFN5eZxsg4QNt4AqFKEwUj9PewoxQMU/0sK28R7LbjKxznYWxhdwRnH10PT+x5nlRmYMPDBtey77ELHvM9dCd1pFYaFlqZ5RP/rbQVcgIA0CQjHGIl/Po= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783011450; c=relaxed/simple; bh=cx9eZGI21BGaiJDAAtjYDTuYF4X4cdxYpNKmaCdngoQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PjbypjbuSckHNf3mvG5zZR2+OCObOB+g7Q21FYqvU6FXPdHGwr849e1yHNy+5H9vz9HhQQ7bkFEw5rMisNbZfeQNqmjOeUtyCWQ0k+PHNOHFEHup/hmH/wfKGozpZ6zT1jAuhRfUWFoumPZm0yRLdfumy6/a1Lkgiuzh+D6/8xE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Z4k+Z/KC; 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="Z4k+Z/KC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 774F21F000E9; Thu, 2 Jul 2026 16:57:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783011449; bh=lLNtk5N032MZ2hcfSs51w7DV30y0/n+s+C0B6tYi3r4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Z4k+Z/KCDLQ+EL6HKp+ATEyX6asXzo+QoyIkfuGxQrFBXfmSnb8vLedp8sQFQBVEA sPCam0VInmkwtzJZE+wQ+RoL/Inot+zboSeXYnRx9kIqwdsOEUHQl4wjnvJoBBuA3Y vyMG4cz/tNDEXsv480J9i1q98+oYK2JzaZ0EcoxU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Michael Bommarito , Anna Schumaker Subject: [PATCH 6.18 101/108] NFSv4/flexfiles: reject zero filehandle version count Date: Thu, 2 Jul 2026 18:21:38 +0200 Message-ID: <20260702155114.204437822@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702155112.110058792@linuxfoundation.org> References: <20260702155112.110058792@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michael Bommarito commit 2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2 upstream. 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: Greg Kroah-Hartman --- fs/nfs/flexfilelayout/flexfilelayout.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/fs/nfs/flexfilelayout/flexfilelayout.c +++ b/fs/nfs/flexfilelayout/flexfilelayout.c @@ -552,6 +552,10 @@ ff_layout_alloc_lseg(struct pnfs_layout_ if (!p) goto out_err_free; fh_count = be32_to_cpup(p); + if (fh_count == 0) { + rc = -EINVAL; + goto out_err_free; + } dss_info->fh_versions = kcalloc(fh_count, sizeof(struct nfs_fh),