Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: wifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work The brcmf_btcoex_detach() only shuts down the btcoex timer, if the flag timer_on is false. However, the brcmf_btcoex_timerfunc(), which runs as timer handler, sets timer_on to false. This creates critical race conditions: 1.If brcmf_btcoex_detach() is called while brcmf_btcoex_timerfunc() is executing, it may observe timer_on as false and skip the call to timer_shutdown_sync(). 2.The brcmf_btcoex_timerfunc() may then reschedule the brcmf_btcoex_info worker after the cancel_work_sync() has been executed, resulting in use-after-free bugs. The use-after-free bugs occur in two distinct scenarios, depending on the timing of when the brcmf_btcoex_info struct is freed relative to the execution of its worker thread. Scenario 1: Freed before the worker is scheduled The brcmf_btcoex_info is deallocated before the worker is scheduled. A race condition can occur when schedule_work(&bt_local->work) is called after the target memory has been freed. The sequence of events is detailed below: CPU0 | CPU1 brcmf_btcoex_detach | brcmf_btcoex_timerfunc | bt_local->timer_on = false; if (cfg->btcoex->timer_on) | ... | cancel_work_sync(); | ... | kfree(cfg->btcoex); // FREE | | schedule_work(&bt_local->work); // USE Scenario 2: Freed after the worker is scheduled The brcmf_btcoex_info is freed after the worker has been scheduled but before or during its execution. In this case, statements within the brcmf_btcoex_handler() — such as the container_of macro and subsequent dereferences of the brcmf_btcoex_info object will cause a use-after-free access. The following timeline illustrates this scenario: CPU0 | CPU1 brcmf_btcoex_detach | brcmf_btcoex_timerfunc | bt_local->timer_on = false; if (cfg->btcoex->timer_on) | ... | cancel_work_sync(); | ... | schedule_work(); // Reschedule | kfree(cfg->btcoex); // FREE | brcmf_btcoex_handler() // Worker /* | btci = container_of(....); // USE The kfree() above could | ... also occur at any point | btci-> // USE during the worker's execution| */ | To resolve the race conditions, drop the conditional check and call timer_shutdown_sync() directly. It can deactivate the timer reliably, regardless of its current state. Once stopped, the timer_on state is then set to false.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 61730d4dfffc2cc9d3a49fad87633008105c18ba before c75600e69e66a751cc046cd9c407b942f298d852; affected 61730d4dfffc2cc9d3a49fad87633008105c18ba before ae58f70bde0433f27ef4b388ab50634736607bf6; affected 61730d4dfffc2cc9d3a49fad87633008105c18ba before f1150153c4e5940fe49ab51136343c5b4fe49d63; affected 61730d4dfffc2cc9d3a49fad87633008105c18ba before 3e789f8475f6c857c88de5c5bf4b24b11a477dd7; affected 61730d4dfffc2cc9d3a49fad87633008105c18ba before 2f6fbc8e04ca1d1d5c560be694199f847229c625; affected 61730d4dfffc2cc9d3a49fad87633008105c18ba before 9cb83d4be0b9b697eae93d321e0da999f9cdfcfc |
| Linux / Linux | affected 3.10; unaffected 0 before 3.10; unaffected 5.15.210 through 5.15.*; unaffected 6.1.167 through 6.1.*; unaffected 6.6.105 through 6.6.*; unaffected 6.12.46 through 6.12.*; unaffected 6.16.6 through 6.16.*; unaffected 6.17 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/c75600e69e66a751cc046cd9c407b942f298d852
- https://git.kernel.org/stable/c/ae58f70bde0433f27ef4b388ab50634736607bf6
- https://git.kernel.org/stable/c/f1150153c4e5940fe49ab51136343c5b4fe49d63
- https://git.kernel.org/stable/c/3e789f8475f6c857c88de5c5bf4b24b11a477dd7
- https://git.kernel.org/stable/c/2f6fbc8e04ca1d1d5c560be694199f847229c625
- https://git.kernel.org/stable/c/9cb83d4be0b9b697eae93d321e0da999f9cdfcfc
ADP enrichment
No English description supplied.
No references supplied.
No English description supplied.