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 14F8B1D798E; Sat, 12 Sep 2026 17:02:50 +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=1789232572; cv=none; b=ADzkGtS6iCUx4YCiJBZYaqethRSxZ+NMpDp8883hP1oCAzafuJmw6vM+34LEAsxy6OMsUqMhJjYOz0cIu7g31bYRWsrSzNL74YAG4BkDqfGb3kvvenz8YcchqneBG2xnHr+s1/2eKwWp1SgzH/9DKQYIEkPr3SP1QD6piXFPi4A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789232572; c=relaxed/simple; bh=cuwoS1YUklfObdo5ukJDYvfCQuXFOYNwvfObmbnkdSI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=H28+Rhudl2LGzA4NgFFa2gYvh0FOXm0vZDrSR6BFkxnv9IlExJdEY4pUo6GPAzVDwfZaXRMD8yNCdxwEAGJN3bb02Fzgqc0chXy914MmjOGODBGK+NF63uqkc8/gHHLvcVssATDNUXdaSsINhNUjpjG7ya1qa4XRp6Imvbkk/7Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rrYZQsCL; 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="rrYZQsCL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C29BA1F00893; Sat, 12 Sep 2026 17:02:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789232570; bh=WbHYG20UoZpUDLzk1ugwA/Vt0pJcW+vyP1JOQHA39no=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=rrYZQsCLu3q1RnF0KEN1TmbLa49elasyEaBPrJHy5q+3sutJoLkWTB6OL57mxIKR/ 1MhwFqrqu+U49DgOc/+Yu9nSPl23xPhjOz7ObH7OKGN3cVmUKMIKGrn772cldZeWl6 XeEPd+kYsZDYIhR90hEd6GWh6ecPMzh5GWUvetR4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ibrahim Hashimov , Richard Weinberger , Zhihao Cheng Subject: [PATCH 5.15 030/935] ubifs: fix out-of-bounds read in signature length check Date: Sat, 12 Sep 2026 08:51:00 +0200 Message-ID: <20260912065527.531341566@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065526.833703348@linuxfoundation.org> References: <20260912065526.833703348@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ibrahim Hashimov commit 95d27c1708bb6e8823c8e7c623f9abc2a91bf4bf upstream. ubifs_sb_verify_signature() bounds the on-disk ubifs_sig_node->len field before handing the signature payload to verify_pkcs7_signature(), but the check has the wrong sign: if (le32_to_cpu(signode->len) > snod->len + sizeof(struct ubifs_sig_node)) The signature bytes start sizeof(struct ubifs_sig_node) (UBIFS_SIG_NODE_SZ, 64 bytes) into the node, so the payload is at most snod->len - sizeof(struct ubifs_sig_node) bytes long. Adding the header size instead of subtracting it accepts a declared length up to 2 * UBIFS_SIG_NODE_SZ larger than the node actually holds -- past the end of c->sbuf, which is vmalloc(c->leb_size). verify_pkcs7_signature() -> pkcs7_parse_message() -> asn1_ber_decoder() is then handed that inflated length and reads beyond the allocation while walking the DER headers. The node length comes straight from the mounted image, so a crafted signed UBIFS image reaches this via ubifs_read_superblock() before the signature is cryptographically checked. snod->len is guaranteed to be >= UBIFS_SIG_NODE_SZ by the node scanner (c->ranges[UBIFS_SIG_NODE].min_len == UBIFS_SIG_NODE_SZ), so the corrected subtraction cannot underflow. Legitimately signed images are unaffected: a correct superblock never declares a signature longer than the node it is embedded in. Fixes: 817aa094842d ("ubifs: support offline signed images") Cc: stable@vger.kernel.org Signed-off-by: Ibrahim Hashimov Assisted-by: AuditCode-AI:2026.07 Reviewed-by: Richard Weinberger Reviewed-by: Zhihao Cheng Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman --- fs/ubifs/auth.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/ubifs/auth.c +++ b/fs/ubifs/auth.c @@ -218,7 +218,7 @@ int ubifs_sb_verify_signature(struct ubi signode = snod->node; - if (le32_to_cpu(signode->len) > snod->len + sizeof(struct ubifs_sig_node)) { + if (le32_to_cpu(signode->len) > snod->len - sizeof(struct ubifs_sig_node)) { ubifs_err(c, "invalid signature len %d", le32_to_cpu(signode->len)); err = -EINVAL; goto out_destroy;