From: Eugene Korenevsky ekorenevsky@astralinux.ru
commit a637f4ae037e1e0604ac008564934d63261a8fd1 upstream.
If smb3_notify() is called at mount point of CIFS, build_path_from_dentry() returns the pointer to kmalloc-ed memory with terminating zero (this is empty FileName to be passed to SMB2 CREATE request). This pointer is assigned to the `path` variable. Then `path + 1` (to skip first backslash symbol) is passed to cifs_convert_path_to_utf16(). This is incorrect for empty path and causes out-of-bound memory access.
Get rid of this "increase by one". cifs_convert_path_to_utf16() already contains the check for leading backslash in the path.
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=212693 CC: stable@vger.kernel.org # v5.6+ Signed-off-by: Eugene Korenevsky ekorenevsky@astralinux.ru Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/cifs/smb2ops.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -2201,7 +2201,7 @@ smb3_notify(const unsigned int xid, stru
cifs_sb = CIFS_SB(inode->i_sb);
- utf16_path = cifs_convert_path_to_utf16(path + 1, cifs_sb); + utf16_path = cifs_convert_path_to_utf16(path, cifs_sb); if (utf16_path == NULL) { rc = -ENOMEM; goto notify_exit;