[PATCH 6.18 041/752] smb: client: prevent races in ->query_interfaces()

Sasha Levin
2026-02-28T17:48:43Z

From: Henrique Carvalho <henrique.carvalho@suse.com>

[ Upstream commit c3c06e42e1527716c54f3ad2ced6a034b5f3a489 ]

It was possible for two query interface works to be concurrently trying
to update the interfaces.

Prevent this by checking and updating iface_last_update under
iface_lock.

Signed-off-by: Henrique Carvalho <henrique.carvalho@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/smb/client/smb2ops.c | 19 ++++++++-----------
1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 1e39f2165e427..c3c5fddb2caab 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -637,13 +637,6 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
p = buf;

spin_lock(&ses->iface_lock);
- /* do not query too frequently, this time with lock held */
- if (ses->iface_last_update &&
- time_before(jiffies, ses->iface_last_update +
- (SMB_INTERFACE_POLL_INTERVAL * HZ))) {
- spin_unlock(&ses->iface_lock);
- return 0;
- }

/*
* Go through iface_list and mark them as inactive
@@ -666,7 +659,6 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
"Empty network interface list returned by server %s\n",
ses->server->hostname);
rc = -EOPNOTSUPP;
- ses->iface_last_update = jiffies;
goto out;
}

@@ -795,8 +787,6 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
+ sizeof(p->Next) && p->Next))
cifs_dbg(VFS, "%s: incomplete interface info\n", __func__);

- ses->iface_last_update = jiffies;
-
out:
/*
* Go through the list again and put the inactive entries
@@ -825,10 +815,17 @@ SMB3_request_interfaces(const unsigned int xid, struct cifs_tcon *tcon, bool in_
struct TCP_Server_Info *pserver;

/* do not query too frequently */
+ spin_lock(&ses->iface_lock);
if (ses->iface_last_update &&
time_before(jiffies, ses->iface_last_update +
- (SMB_INTERFACE_POLL_INTERVAL * HZ)))
+ (SMB_INTERFACE_POLL_INTERVAL * HZ))) {
+ spin_unlock(&ses->iface_lock);
return 0;
+ }
+
+ ses->iface_last_update = jiffies;
+
+ spin_unlock(&ses->iface_lock);

rc = SMB2_ioctl(xid, tcon, NO_FILE_ID, NO_FILE_ID,
FSCTL_QUERY_NETWORK_INTERFACE_INFO,
--
2.51.0