From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7BC4412F585; Mon, 6 Apr 2026 13:49:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775483381; cv=none; b=brNjZnXoSiJPpPkpz5mQATk4R0nQ6UVI8myQ2rZwfs8DAQpowfuaduOHH/wxiqfDSEU1773n5c4uDFI2bBKRNr+03fjk0MvixGtDTjdBfPA1oddIWqZEJgauLfVW51P6/GBekpgMIgp7HfC0FvCO444xCdaOBMAvAo6JT4HHy6s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775483381; c=relaxed/simple; bh=9BU9EIZ0xpSJhe6BLo5bEcq83MnOBqIILZ9FwVVRilI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=u5C6Ye1JK+N7bxSbbEI36yJm1JnWaCYvt/fFCSCDMy3K3tW44unhpQu21ueCkCavqXbUkOhrwzuzfpHCzSF53gAFZadPh0x3HTyiyk6DXX6kFcBGdr6Y6+rgMg+iJ3/RLPENlkSyhF1sj+7Min8pGY8WMi2stjj+CSNx3G4mjFs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=To6h9XC5; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="To6h9XC5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B03D6C4CEF7; Mon, 6 Apr 2026 13:49:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775483381; bh=9BU9EIZ0xpSJhe6BLo5bEcq83MnOBqIILZ9FwVVRilI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=To6h9XC5zP+xWBz0FzFGxcHhdJiVt7QI1Vq9SU297CnmbumwIuUx3EZTpmP1fihB1 iQLu5GNl/TLRxXOf+HGpB60h3/kd/cMpbPp5R6WRDk4Gv2I1McfDfi49yfPm2SxRWF Wbz/f4FCxG6xmntVxIB6Qt/qW+KmUp9Dn/tzASKg= From: Greg Kroah-Hartman To: linux-cifs@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Steve French , Paulo Alcantara , Ronnie Sahlberg , Shyam Prasad N , Tom Talpey , Bharath SM , samba-technical@lists.samba.org, stable Subject: [PATCH 1/2] smb: client: fix off-by-8 bounds check in check_wsl_eas() Date: Mon, 6 Apr 2026 15:49:37 +0200 Message-ID: <2026040636-unsigned-jackal-e239@gregkh> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026040635-banking-unsoiled-3250@gregkh> References: <2026040635-banking-unsoiled-3250@gregkh> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1895; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=9BU9EIZ0xpSJhe6BLo5bEcq83MnOBqIILZ9FwVVRilI=; b=owGbwMvMwCRo6H6F97bub03G02pJDJmXd37YvON0Y+CLz8fKbul+Pt/QzS5tbfrrpeC17U+3n 5Pe+GPJxY5YFgZBJgZZMUWWL9t4ju6vOKToZWh7GmYOKxPIEAYuTgGYSPcxhvklT4Lt51b5zRRO /3AqezXzJP1TBlcYFlyZd2OJ5PuqTwc9jvWucA059fXE/yUA X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit The bounds check uses (u8 *)ea + nlen + 1 + vlen as the end of the EA name and value, but ea_data sits at offset sizeof(struct smb2_file_full_ea_info) = 8 from ea, not at offset 0. The strncmp() later reads ea->ea_data[0..nlen-1] and the value bytes follow at ea_data[nlen+1..nlen+vlen], so the actual end is ea->ea_data + nlen + 1 + vlen. Isn't pointer math fun? The earlier check (u8 *)ea > end - sizeof(*ea) only guarantees the 8-byte header is in bounds, but since the last EA is placed within 8 bytes of the end of the response, the name and value bytes are read past the end of iov. Fix this mess all up by using ea->ea_data as the base for the bounds check. An "untrusted" server can use this to leak up to 8 bytes of kernel heap into the EA name comparison and influence which WSL xattr the data is interpreted as. Cc: Steve French Cc: Paulo Alcantara Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Cc: stable Assisted-by: gregkh_clanker_t1000 Signed-off-by: Greg Kroah-Hartman --- fs/smb/client/smb2inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c index 364bdcff9c9d..fe1c9d776580 100644 --- a/fs/smb/client/smb2inode.c +++ b/fs/smb/client/smb2inode.c @@ -128,7 +128,7 @@ static int check_wsl_eas(struct kvec *rsp_iov) nlen = ea->ea_name_length; vlen = le16_to_cpu(ea->ea_value_length); if (nlen != SMB2_WSL_XATTR_NAME_LEN || - (u8 *)ea + nlen + 1 + vlen > end) + (u8 *)ea->ea_data + nlen + 1 + vlen > end) return -EINVAL; switch (vlen) { -- 2.53.0