6.6-stable review patch. If anyone has any objections, please let me know.
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From: Paul Aurich paul@darkrain42.org
commit 3ca02e63edccb78ef3659bebc68579c7224a6ca2 upstream.
A pre-existing valid cfid returned from find_or_create_cached_dir might race with a lease break, meaning open_cached_dir doesn't consider it valid, and thinks it's newly-constructed. This leaks a dentry reference if the allocation occurs before the queued lease break work runs.
Avoid the race by extending holding the cfid_list_lock across find_or_create_cached_dir and when the result is checked.
Cc: stable@vger.kernel.org Reviewed-by: Henrique Carvalho henrique.carvalho@suse.com Signed-off-by: Paul Aurich paul@darkrain42.org Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/smb/client/cached_dir.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-)
--- a/fs/smb/client/cached_dir.c +++ b/fs/smb/client/cached_dir.c @@ -29,7 +29,6 @@ static struct cached_fid *find_or_create { struct cached_fid *cfid;
- spin_lock(&cfids->cfid_list_lock); list_for_each_entry(cfid, &cfids->entries, entry) { if (!strcmp(cfid->path, path)) { /* @@ -38,25 +37,20 @@ static struct cached_fid *find_or_create * being deleted due to a lease break. */ if (!cfid->time || !cfid->has_lease) { - spin_unlock(&cfids->cfid_list_lock); return NULL; } kref_get(&cfid->refcount); - spin_unlock(&cfids->cfid_list_lock); return cfid; } } if (lookup_only) { - spin_unlock(&cfids->cfid_list_lock); return NULL; } if (cfids->num_entries >= max_cached_dirs) { - spin_unlock(&cfids->cfid_list_lock); return NULL; } cfid = init_cached_dir(path); if (cfid == NULL) { - spin_unlock(&cfids->cfid_list_lock); return NULL; } cfid->cfids = cfids; @@ -74,7 +68,6 @@ static struct cached_fid *find_or_create */ cfid->has_lease = true;
- spin_unlock(&cfids->cfid_list_lock); return cfid; }
@@ -185,8 +178,10 @@ replay_again: if (!utf16_path) return -ENOMEM;
+ spin_lock(&cfids->cfid_list_lock); cfid = find_or_create_cached_dir(cfids, path, lookup_only, tcon->max_cached_dirs); if (cfid == NULL) { + spin_unlock(&cfids->cfid_list_lock); kfree(utf16_path); return -ENOENT; } @@ -195,7 +190,6 @@ replay_again: * Otherwise, it is either a new entry or laundromat worker removed it * from @cfids->entries. Caller will put last reference if the latter. */ - spin_lock(&cfids->cfid_list_lock); if (cfid->has_lease && cfid->time) { spin_unlock(&cfids->cfid_list_lock); *ret_cfid = cfid;