test0r
b717251598
bes2600_bss_info_changed() and bes2600_hw_scan() can run concurrently.
The probe-request SKB allocated by ieee80211_probereq_get() before
scan.lock + conf_lock are taken can be touched by a concurrent
bss_info_changed (via wsm_set_template_frame's path) while we hold no
lock. Reorder to acquire both locks BEFORE the SKB allocation.
Also reorder cleanup paths so dev_kfree_skb() runs BEFORE up() —
otherwise a small window exists where the SKB has been touched but the
lock has been released, allowing concurrent code to also touch it.
Three sites fixed:
- bes2600_hw_scan: lock-take + ENOMEM cleanup + wsm_set_template_frame
error cleanup + success-path SKB free + lock release order
- bes2600_sched_scan_start (#ifdef ROAM_OFFLOAD): same three sub-fixes
(compiled-out at default build, fixed for consistency)
- All success/error paths: dev_kfree_skb before up()
Backport of cw1200 mainline commit 86760e0dfe36 ("cw1200: Fix
concurrency use-after-free bugs in cw1200_hw_scan()", 2018-12-14),
which fixed the identical bug in the same code shape we inherited.
That commit was merged from upstream 4f68ef64cd7f.
Cherry-picked from upstream Linux:
86760e0dfe36 cw1200: Fix concurrency use-after-free bugs in cw1200_hw_scan()
Author: Jia-Ju Bai <baijiaju1990@gmail.com>
Link: https://lore.kernel.org/r/20181214035521.7575-1-baijiaju1990@gmail.com