4.18-stable review patch. If anyone has any objections, please let me know.
------------------ From: Dan Carpenter <dan.carpen...@oracle.com> commit 2d204ee9d671327915260071c19350d84344e096 upstream. The "le32_to_cpu(rsp->OutputOffset) + *plen" addition can overflow and wrap around to a smaller value which looks like it would lead to an information leak. Fixes: 4a72dafa19ba ("SMB2 FSCTL and IOCTL worker function") Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com> Signed-off-by: Steve French <stfre...@microsoft.com> Reviewed-by: Aurelien Aptel <aap...@suse.com> CC: Stable <sta...@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- fs/cifs/smb2pdu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -2418,14 +2418,14 @@ SMB2_ioctl(const unsigned int xid, struc /* We check for obvious errors in the output buffer length and offset */ if (*plen == 0) goto ioctl_exit; /* server returned no data */ - else if (*plen > 0xFF00) { + else if (*plen > rsp_iov.iov_len || *plen > 0xFF00) { cifs_dbg(VFS, "srv returned invalid ioctl length: %d\n", *plen); *plen = 0; rc = -EIO; goto ioctl_exit; } - if (rsp_iov.iov_len < le32_to_cpu(rsp->OutputOffset) + *plen) { + if (rsp_iov.iov_len - *plen < le32_to_cpu(rsp->OutputOffset)) { cifs_dbg(VFS, "Malformed ioctl resp: len %d offset %d\n", *plen, le32_to_cpu(rsp->OutputOffset)); *plen = 0;