Commit 6976c7a6 authored by Wang Zhaolong's avatar Wang Zhaolong Committed by Steve French
Browse files

smb: client: Fix NULL pointer dereference in cifs_debug_dirs_proc_show() 



Reading /proc/fs/cifs/open_dirs may hit a NULL dereference when
tcon->cfids is NULL.

Add NULL check before accessing cfids to prevent the crash.

Reproduction:
- Mount CIFS share
- cat /proc/fs/cifs/open_dirs

Fixes: 844e5c0e ("smb3 client: add way to show directory leases for improved debugging")
Signed-off-by: default avatarWang Zhaolong <wangzhaolong@huaweicloud.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent b320789d

fs/smb/client/cifs_debug.c

+2 −2
Original line number Diff line number Diff line
@@ -304,6 +304,8 @@ static int cifs_debug_dirs_proc_show(struct seq_file *m, void *v) 
			list_for_each(tmp1, &ses->tcon_list) {

				tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);

				cfids = tcon->cfids;

				if (!cfids)

					continue;

				spin_lock(&cfids->cfid_list_lock); /* check lock ordering */

				seq_printf(m, "Num entries: %d\n", cfids->num_entries);

				list_for_each_entry(cfid, &cfids->entries, entry) {
@@ -319,8 +321,6 @@ static int cifs_debug_dirs_proc_show(struct seq_file *m, void *v) 
					seq_printf(m, "\n");

				}

				spin_unlock(&cfids->cfid_list_lock);





			}

		}

	}