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 67BFD23BF9F for ; Sun, 5 Jul 2026 03:11:56 +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=1783221117; cv=none; b=fWMcjSBfl6P+/KXeT/HGK9596+jnqoeDgCgo/BcHFS2l19VskA3dDliNXQFeNlrfPaDkkJtt4hVtCidfjhmxmSTmWs+4MmUyqTQHdOWqHuyJrQ6RCMqP7n7OqRNCLEbay3XE0vV20/N/cv2TXqwALHyeN0hs5V+umMdqB+ahnQw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783221117; c=relaxed/simple; bh=YeelmSk3cumN+KTkcyriivXDUtlQbzOHOnXHV1FLjPQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HMTuiwHQaf96cDHe/HDmzJupg49AiPZqO+TnlnrWaikkgywFhQXoJy+vUCIe4beYpp3w5qFDCuXyt2p2+McoJbQdCvjnJXc3vyQV/SE09R0cjIHNR39OGpBEimgmtIGSbketKzyy3pmGP0Uol1QY9gTx1o+ttNkThs8DE28iFA8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CpTRN+uU; 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="CpTRN+uU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D21F61F00A3A; Sun, 5 Jul 2026 03:11:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783221116; bh=nvIAH+RO5orIMmzXxrRsqa3DaB0LspF9ac/RiiMhay0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=CpTRN+uUCAbPVm91qpxBYb6qv9Blz5ctZwpMbdebHQss50oRtxWA4Qwy3zV+8KMGB hCl58UUp4kMLulEodcYZTK9hddUoWy4d+L8yLrFFqh57kLn3bIb2MXHPhu2rnLnNmC xHxup8d2vUO2Wz8MtPZSQFOsizlooyYVYHaFSoHq6ksA7/j2pxV0VnyiuBI8AYR59i 4t7eaDnpohN8xs0SSfGs8gn+kxsvX4WHe84eGmsJM5mGjesjI6OQ2cIPuoHSwUcDh9 9pC2YKsojP2cTvpa/qysXtz2J909y76FFXkjv5RitximHdZ6PVrnSMH6EiWvY1+upA RFFoGs7rtL4XQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Michael Bommarito , Anna Schumaker , Sasha Levin Subject: [PATCH 6.12.y 5/5] NFSv4/flexfiles: reject zero filehandle version count Date: Sat, 4 Jul 2026 23:11:50 -0400 Message-ID: <20260705031150.1600970-5-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260705031150.1600970-1-sashal@kernel.org> References: <2026070242-poker-barricade-3a69@gregkh> <20260705031150.1600970-1-sashal@kernel.org> 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 36270f6a759ec7..7e1494cc116b29 100644 --- a/fs/nfs/flexfilelayout/flexfilelayout.c +++ b/fs/nfs/flexfilelayout/flexfilelayout.c @@ -493,6 +493,10 @@ 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]->dss[dss_id].fh_versions = kcalloc(fh_count, sizeof(struct nfs_fh), -- 2.53.0