[PATCH 5.13 017/151] cifs: use the correct max-length for dentry_path_raw()

Greg Kroah-Hartman
2021-08-16T13:19:57Z

From: Ronnie Sahlberg <lsahlber@redhat.com>

commit 981567bd965329df7e64b13e92a54da816c1e0a4 upstream.

RHBZ: 1972502

PATH_MAX is 4096 but PAGE_SIZE can be >4096 on some architectures
such as ppc and would thus write beyond the end of the actual object.

Cc: <stable@vger.kernel.org>
Reported-by: Xiaoli Feng <xifeng@redhat.com>
Suggested-by: Brian foster <bfoster@redhat.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/cifs/dir.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -112,7 +112,7 @@ build_path_from_dentry_optional_prefix(s
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH)
pplen = cifs_sb->prepath ? strlen(cifs_sb->prepath) + 1 : 0;

- s = dentry_path_raw(direntry, page, PAGE_SIZE);
+ s = dentry_path_raw(direntry, page, PATH_MAX);
if (IS_ERR(s))
return s;
if (!s[1]) // for root we want "", not "/"