From: Duoming Zhou Date: Tue, 10 Feb 2026 09:45:37 +0000 (+0800) Subject: atm: fore200e: fix use-after-free in tasklets during device removal X-Git-Tag: v7.0-rc1~44^2~44 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8930878101cd40063888a68af73b1b0f8b6c79bc;p=thirdparty%2Fkernel%2Flinux.git atm: fore200e: fix use-after-free in tasklets during device removal When the PCA-200E or SBA-200E adapter is being detached, the fore200e is deallocated. However, the tx_tasklet or rx_tasklet may still be running or pending, leading to use-after-free bug when the already freed fore200e is accessed again in fore200e_tx_tasklet() or fore200e_rx_tasklet(). One of the race conditions can occur as follows: CPU 0 (cleanup) | CPU 1 (tasklet) fore200e_pca_remove_one() | fore200e_interrupt() fore200e_shutdown() | tasklet_schedule() kfree(fore200e) | fore200e_tx_tasklet() | fore200e-> // UAF Fix this by ensuring tx_tasklet or rx_tasklet is properly canceled before the fore200e is released. Add tasklet_kill() in fore200e_shutdown() to synchronize with any pending or running tasklets. Moreover, since fore200e_reset() could prevent further interrupts or data transfers, the tasklet_kill() should be placed after fore200e_reset() to prevent the tasklet from being rescheduled in fore200e_interrupt(). Finally, it only needs to do tasklet_kill() when the fore200e state is greater than or equal to FORE200E_STATE_IRQ, since tasklets are uninitialized in earlier states. In a word, the tasklet_kill() should be placed in the FORE200E_STATE_IRQ branch within the switch...case structure. This bug was identified through static analysis. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@kernel.org Suggested-by: Jijie Shao Signed-off-by: Duoming Zhou Reviewed-by: Jijie Shao Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260210094537.9767-1-duoming@zju.edu.cn Signed-off-by: Jakub Kicinski --- diff --git a/drivers/atm/fore200e.c b/drivers/atm/fore200e.c index f62e385714403..fec081db36dc4 100644 --- a/drivers/atm/fore200e.c +++ b/drivers/atm/fore200e.c @@ -373,6 +373,10 @@ fore200e_shutdown(struct fore200e* fore200e) fallthrough; case FORE200E_STATE_IRQ: free_irq(fore200e->irq, fore200e->atm_dev); +#ifdef FORE200E_USE_TASKLET + tasklet_kill(&fore200e->tx_tasklet); + tasklet_kill(&fore200e->rx_tasklet); +#endif fallthrough; case FORE200E_STATE_ALLOC_BUF: