CVE-2026-98406

In the Linux kernel, the following vulnerability has been resolved:

wifi: mac80211: avoid WARN in set_bitrate_mask when sdata not in driver

ieee80211_set_bitrate_mask() checks if the interface is running via ieee80211_sdata_running(), but it does not check if the interface is still present in the driver.

When sdata is running but IEEE80211_SDATA_IN_DRIVER is not set, the call reaches drv_set_bitrate_mask() in driver-ops.h which hits

wlan1: Failed check-sdata-in-driver check, flags: 0x0 WARNING: net/mac80211/driver-ops.h:884 at drv_set_bitrate_mask

Syzkaller triggers this via wext SIOCSIWRATE ioctl. The Call Trace shows wext_ioctl_dispatch() in wext-core.c dispatching the ioctl, calling ioctl_standard_call() for SIOCSIWRATE, which calls cfg80211_wext_siwrate() in wext-compat.c. That builds a bitrate mask and calls rdev_set_bitrate_mask() which ends up in ieee80211_set_bitrate_mask() in cfg.c. The interface is marked running via SDATA_STATE_RUNNING but flags is 0, so check_sdata_in_driver() fails.

When the interface is being torn down, or when wext ioctl is issued during interface bringup before drv_add_interface() sets IN_DRIVER, the running check passes while IN_DRIVER is clear.

Check IEEE80211_SDATA_IN_DRIVER in ieee80211_set_bitrate_mask() before calling the driver, returning -ENETDOWN. This avoids the WARN_ONCE in driver-ops.h and matches other cfg.c operations that bail early when not in driver.

This change should be safe because wiphy mutex is held in cfg80211_wext_siwrate() via guard(wiphy), and IN_DRIVER is set/cleared under RTNL and wiphy paths in drv_add_interface() and drv_remove_interface() in driver-ops.c, so the check is race-free against driver add/remove. Returning -ENETDOWN is the same error other not-running paths use and does not introduce new locking.

[also add second syzbot report]

Affected Software

References

• https://git.kernel.org/stable/c/0d1700394e9f5d0bd9bebad8d5a50edf983f52fd
• https://git.kernel.org/stable/c/4095b66acae9893dd13deb39a4331651cb2f822b
• https://git.kernel.org/stable/c/432c8532d5ccc2af77da43ed6ef1c80495a4efe8
• https://git.kernel.org/stable/c/4ba86c44b2fcb1c3175caa2456b6d58f483446ab
• https://git.kernel.org/stable/c/7978dda63d2b109ea9c3f7a096cd1aac6542cd54
• https://git.kernel.org/stable/c/c2cd9c44777cf97be3e35c10b7c2d8f59ebb9306
• https://git.kernel.org/stable/c/c4ee5685af444024e6222ce29f6ed36adc44ffc3
• https://git.kernel.org/stable/c/da2ca406f45a6e21760243152ed8d2e8e72915c2