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. 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 --- Changes in v3: - Only do tasklet_kill() when state >= FORE200E_STATE_IRQ. - Make the commit messages clearer. drivers/atm/fore200e.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/atm/fore200e.c b/drivers/atm/fore200e.c index f62e3857144..eb386ec6b5e 100644 --- a/drivers/atm/fore200e.c +++ b/drivers/atm/fore200e.c @@ -363,7 +363,12 @@ fore200e_shutdown(struct fore200e* fore200e) /* first, reset the board to prevent further interrupts or data transfers */ fore200e_reset(fore200e, 0); } - +#ifdef FORE200E_USE_TASKLET + if (fore200e->state >= FORE200E_STATE_IRQ) { + tasklet_kill(&fore200e->tx_tasklet); + tasklet_kill(&fore200e->rx_tasklet); + } +#endif /* then, release all allocated resources */ switch(fore200e->state) { -- 2.34.1