From 6976c7a69dafbb34a0d4814e2def9d3d7114836d Mon Sep 17 00:00:00 2001 From: Wang Zhaolong Date: Fri, 29 Aug 2025 08:59:59 +0800 Subject: [PATCH] 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: 844e5c0eb176 ("smb3 client: add way to show directory leases for improved debugging") Signed-off-by: Wang Zhaolong Signed-off-by: Steve French --- fs/smb/client/cifs_debug.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/smb/client/cifs_debug.c b/fs/smb/client/cifs_debug.c index beb4f18f05ef1..edb2e7f7fc23a 100644 --- a/fs/smb/client/cifs_debug.c +++ b/fs/smb/client/cifs_debug.c @@ -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); - - } } } -- 2.39.5