From: Marek Szyprowski Date: Thu, 16 Apr 2026 09:33:39 +0000 (+0200) Subject: wifi: brcmfmac: Fix potential use-after-free issue when stopping watchdog task X-Git-Tag: v7.1-rc3~26^2~22^2~17 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c623b63580880cc742255eaed3d79804c1b91143;p=thirdparty%2Fkernel%2Flinux.git wifi: brcmfmac: Fix potential use-after-free issue when stopping watchdog task Watchdog task might end between send_sig() and kthread_stop() calls, what results in the use-after-free issue. Fix this by increasing watchdog task reference count before calling send_sig() and dropping it by switching to kthread_stop_put(). Cc: stable@vger.kernel.org Fixes: 373c83a801f1 ("brcmfmac: stop watchdog before detach and free everything") Fixes: a9ffda88be74 ("brcm80211: fmac: abstract bus_stop interface function pointer") Signed-off-by: Marek Szyprowski Acked-by: Arend van Spriel Link: https://patch.msgid.link/20260416093339.2066829-1-m.szyprowski@samsung.com Signed-off-by: Johannes Berg --- diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c index 30f6fcb68632..8fb595733b9c 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c @@ -2476,8 +2476,9 @@ static void brcmf_sdio_bus_stop(struct device *dev) brcmf_dbg(TRACE, "Enter\n"); if (bus->watchdog_tsk) { + get_task_struct(bus->watchdog_tsk); send_sig(SIGTERM, bus->watchdog_tsk, 1); - kthread_stop(bus->watchdog_tsk); + kthread_stop_put(bus->watchdog_tsk); bus->watchdog_tsk = NULL; } @@ -4567,8 +4568,9 @@ void brcmf_sdio_remove(struct brcmf_sdio *bus) if (bus) { /* Stop watchdog task */ if (bus->watchdog_tsk) { + get_task_struct(bus->watchdog_tsk); send_sig(SIGTERM, bus->watchdog_tsk, 1); - kthread_stop(bus->watchdog_tsk); + kthread_stop_put(bus->watchdog_tsk); bus->watchdog_tsk = NULL; }