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| author | Jakub Kicinski <kuba@kernel.org> | 2026-04-10 08:36:00 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-04-12 09:08:43 -0700 |
| commit | 0aa72fc37e15974827ceb72c5cf8e57085a29301 (patch) | |
| tree | bbc38c2efac3c44525d3747970ca813abdc890b4 /net/core | |
| parent | f5148298b0fe18cc91f07584bd0f75cbace3cece (diff) | |
| download | lwn-0aa72fc37e15974827ceb72c5cf8e57085a29301.tar.gz lwn-0aa72fc37e15974827ceb72c5cf8e57085a29301.zip | |
net: fix reference tracker mismanagement in netdev_put_lock()
dev_put() releases a reference which didn't have a tracker.
References without a tracker are accounted in the tracking
code as "no_tracker". We can't free the tracker and then
call dev_put(). The references themselves will be fine
but the tracking code will think it's a double-release:
refcount_t: decrement hit 0; leaking memory.
IOW commit under fixes confused dev_put() (release never tracked
reference) with __dev_put() (just release the reference, skipping
the reference tracking infra).
Since __netdev_put_lock() uses dev_put() we can't feed a previously
tracked netdev ref into it. Let's flip things around.
netdev_put(dev, NULL) is the same as dev_put(dev) so make
netdev_put_lock() the real function and have __netdev_put_lock()
feed it a NULL tracker for all the cases that were untracked.
Fixes: d04686d9bc86 ("net: Implement netdev_nl_queue_create_doit")
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://patch.msgid.link/20260410153600.1984522-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/dev.c | 16 | ||||
| -rw-r--r-- | net/core/dev.h | 8 |
2 files changed, 12 insertions, 12 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index ccc4418b3163..e59f6025067c 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1060,16 +1060,18 @@ struct net_device *dev_get_by_napi_id(unsigned int napi_id) * This helper is intended for locking net_device after it has been looked up * using a lockless lookup helper. Lock prevents the instance from going away. */ -struct net_device *__netdev_put_lock(struct net_device *dev, struct net *net) +struct net_device * +netdev_put_lock(struct net_device *dev, struct net *net, + netdevice_tracker *tracker) { netdev_lock(dev); if (dev->reg_state > NETREG_REGISTERED || dev->moving_ns || !net_eq(dev_net(dev), net)) { netdev_unlock(dev); - dev_put(dev); + netdev_put(dev, tracker); return NULL; } - dev_put(dev); + netdev_put(dev, tracker); return dev; } @@ -1122,14 +1124,6 @@ netdev_get_by_index_lock_ops_compat(struct net *net, int ifindex) } struct net_device * -netdev_put_lock(struct net_device *dev, struct net *net, - netdevice_tracker *tracker) -{ - netdev_tracker_free(dev, tracker); - return __netdev_put_lock(dev, net); -} - -struct net_device * netdev_xa_find_lock(struct net *net, struct net_device *dev, unsigned long *index) { diff --git a/net/core/dev.h b/net/core/dev.h index 376bac4a82da..628bdaebf0ca 100644 --- a/net/core/dev.h +++ b/net/core/dev.h @@ -31,9 +31,15 @@ struct napi_struct * netdev_napi_by_id_lock(struct net *net, unsigned int napi_id); struct net_device *dev_get_by_napi_id(unsigned int napi_id); -struct net_device *__netdev_put_lock(struct net_device *dev, struct net *net); struct net_device *netdev_put_lock(struct net_device *dev, struct net *net, netdevice_tracker *tracker); + +static inline struct net_device * +__netdev_put_lock(struct net_device *dev, struct net *net) +{ + return netdev_put_lock(dev, net, NULL); +} + struct net_device * netdev_xa_find_lock(struct net *net, struct net_device *dev, unsigned long *index); |