smb: client: Reset all search buffer pointers when releasing buffer

commit e48f9d849bfdec276eebf782a84fd4dfbe1c14c0 upstream.

Multiple pointers in struct cifs_search_info (ntwrk_buf_start,
srch_entries_start, and last_entry) point to the same allocated buffer.
However, when freeing this buffer, only ntwrk_buf_start was set to NULL,
while the other pointers remained pointing to freed memory.

This is defensive programming to prevent potential issues with stale
pointers. While the active UAF vulnerability is fixed by the previous
patch, this change ensures consistent pointer state and more robust error
handling.

Signed-off-by: Wang Zhaolong <wangzhaolong1@huawei.com>
Cc: stable@vger.kernel.org
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/smb/client/readdir.c b/fs/smb/client/readdir.c
index 338e4cd81fbd50442872fb60dd6ab699732b9932..402ac06ae9b6f9ac2574d14bc6dba7ec12a7ecf4 100644 (file)
--- a/fs/smb/client/readdir.c
+++ b/fs/smb/client/readdir.c
@@ -765,7 +765,10 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos,
                        else
                                cifs_buf_release(cfile->srch_inf.
                                                ntwrk_buf_start);
+                       /* Reset all pointers to the network buffer to prevent stale references */
                        cfile->srch_inf.ntwrk_buf_start = NULL;
+                       cfile->srch_inf.srch_entries_start = NULL;
+                       cfile->srch_inf.last_entry = NULL;
                }
                rc = initiate_cifs_search(xid, file, full_path);
                if (rc) {