When the qla2xxx firmware is unavailable, eventually qla2x00_sp_timeout() is reached, which calls the timeout function and frees the srb_t instance. The timeout function always resolves to qla2x00_async_iocb_timeout(), which invokes another callback function called "done". All of these qla2x00_*_sp_done() callbacks also free the srb_t instance; after returning to qla2x00_sp_timeout(), it is freed again. The fix is to remove the "sp->free(sp)" call from qla2x00_sp_timeout() and add it to those code paths in qla2x00_async_iocb_timeout() which do not already free the object. This is how it looks like with KASAN: BUG: KASAN: use-after-free in qla2x00_sp_timeout+0x228/0x250 Read of size 8 at addr ffff88278147a590 by task swapper/2/0 Allocated by task 1502: save_stack+0x33/0xa0 kasan_kmalloc+0xa0/0xd0 kmem_cache_alloc+0xb8/0x1c0 mempool_alloc+0xd6/0x260 qla24xx_async_gnl+0x3c5/0x1100 Freed by task 0: save_stack+0x33/0xa0 kasan_slab_free+0x72/0xc0 kmem_cache_free+0x75/0x200 qla24xx_async_gnl_sp_done+0x556/0x9e0 qla2x00_async_iocb_timeout+0x1c7/0x420 qla2x00_sp_timeout+0x16d/0x250 call_timer_fn+0x36/0x200 The buggy address belongs to the object at ffff88278147a440 which belongs to the cache qla2xxx_srbs of size 344 The buggy address is located 336 bytes inside of 344-byte region [ffff88278147a440, ffff88278147a598) Signed-off-by: Max Kellermann <mk@xxxxxxxxxx> --- drivers/scsi/qla2xxx/qla_init.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/qla2xxx/qla_init.c b/drivers/scsi/qla2xxx/qla_init.c index b5b48ddca962..801890564e00 100644 --- a/drivers/scsi/qla2xxx/qla_init.c +++ b/drivers/scsi/qla2xxx/qla_init.c @@ -58,7 +58,6 @@ qla2x00_sp_timeout(unsigned long __data) req->outstanding_cmds[sp->handle] = NULL; iocb = &sp->u.iocb_cmd; iocb->timeout(sp); - sp->free(sp); spin_unlock_irqrestore(&vha->hw->hardware_lock, flags); } @@ -121,9 +120,11 @@ qla2x00_async_iocb_timeout(void *data) ea.data[1] = lio->u.logio.data[1]; ea.sp = sp; qla24xx_handle_plogi_done_event(fcport->vha, &ea); + sp->free(sp); break; case SRB_LOGOUT_CMD: qlt_logo_completion_handler(fcport, QLA_FUNCTION_TIMEOUT); + sp->free(sp); break; case SRB_CT_PTHRU_CMD: case SRB_MB_IOCB:
