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

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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: 844e5c0eb1 ("smb3 client: add way to show directory leases for improved debugging")
Signed-off-by: Wang Zhaolong <wangzhaolong@huaweicloud.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Wang Zhaolong 2025-08-29 08:59:59 +08:00 committed by Steve French
parent b320789d68
commit 6976c7a69d
1 changed files with 2 additions and 2 deletions
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4
fs/smb/client/cifs_debug.c
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@ -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);
}
}
}