[PATCH net v2] wifi: mac80211: fix memory leak in ieee80211_register_hw()

[Dawei Feng]

If kmemdup() fails while copying supported band structures, the error
path jumps to fail_rate. This skips rate_control_deinitialize() and
leaks the initialized local->rate_ctrl.

Fix this by adding a fail_band label that shares the rate-control cleanup
path before falling through to the remaining teardown.

The bug was first flagged by an experimental analysis tool we are
developing for kernel memory-management bugs while analyzing
v6.13-rc1. The tool is still under development and is not yet publicly
available. Manual inspection confirms that the bug is still present in
v7.1-rc7.

An x86_64 allyesconfig build showed no new warnings. As we do not have a
suitable mac80211 device/driver combination to test with, no runtime
testing was able to be performed.

Fixes: 09b4a4faf9d0 ("mac80211: introduce capability flags for VHT EXT NSS support")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Zilin Guan <zilin@xxxxxxxxxx>
Signed-off-by: Dawei Feng <dawei.feng@xxxxxxxxxx>
---
Changes in v2:
- Add a fail_band label for the band-copy failure path instead of jumping
  directly to fail_wiphy_register.

 net/mac80211/main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index f47dd58770ad..dba66dd964af 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -1599,7 +1599,7 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 		sband = kmemdup(sband, sizeof(*sband), GFP_KERNEL);
 		if (!sband) {
 			result = -ENOMEM;
-			goto fail_rate;
+			goto fail_band;
 		}
 
 		wiphy_dbg(hw->wiphy, "copying sband (band %d) due to VHT EXT NSS BW flag\n",
@@ -1675,6 +1675,7 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 #endif
 	wiphy_unregister(local->hw.wiphy);
  fail_wiphy_register:
+ fail_band:
 	rtnl_lock();
 	rate_control_deinitialize(local);
 	ieee80211_remove_interfaces(local);
-- 
2.34.1