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scsi: qla2xxx: Fix double free bug after firmware timeout

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This patch is based on Max's original patch.

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)

Reported-by: Max Kellermann <mk@cm4all.com>
Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Cc: Max Kellermann <mk@cm4all.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Quinn Tran 2018-02-01 10:33:17 -08:00 committed by Martin K. Petersen
parent cabe92a55e
commit eaf75d1815
1 changed files with 3 additions and 20 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

23
drivers/scsi/qla2xxx/qla_init.c
View file

@ -59,8 +59,6 @@ qla2x00_sp_timeout(struct timer_list *t)
req->outstanding_cmds[sp->handle] = NULL;
iocb = &sp->u.iocb_cmd;
iocb->timeout(sp);
if (sp->type != SRB_ELS_DCMD)
sp->free(sp);
spin_unlock_irqrestore(&vha->hw->hardware_lock, flags);
}
@ -102,7 +100,6 @@ qla2x00_async_iocb_timeout(void *data)
srb_t *sp = data;
fc_port_t *fcport = sp->fcport;
struct srb_iocb *lio = &sp->u.iocb_cmd;
struct event_arg ea;
if (fcport) {
ql_dbg(ql_dbg_disc, fcport->vha, 0x2071,
@ -117,25 +114,13 @@ qla2x00_async_iocb_timeout(void *data)
switch (sp->type) {
case SRB_LOGIN_CMD:
if (!fcport)
break;
/* Retry as needed. */
lio->u.logio.data[0] = MBS_COMMAND_ERROR;
lio->u.logio.data[1] = lio->u.logio.flags & SRB_LOGIN_RETRIED ?
QLA_LOGIO_LOGIN_RETRIED : 0;
memset(&ea, 0, sizeof(ea));
ea.event = FCME_PLOGI_DONE;
ea.fcport = sp->fcport;
ea.data[0] = lio->u.logio.data[0];
ea.data[1] = lio->u.logio.data[1];
ea.sp = sp;
qla24xx_handle_plogi_done_event(fcport->vha, &ea);
sp->done(sp, QLA_FUNCTION_TIMEOUT);
break;
case SRB_LOGOUT_CMD:
if (!fcport)
break;
qlt_logo_completion_handler(fcport, QLA_FUNCTION_TIMEOUT);
break;
case SRB_CT_PTHRU_CMD:
case SRB_MB_IOCB:
case SRB_NACK_PLOGI:
@ -235,12 +220,10 @@ static void
qla2x00_async_logout_sp_done(void *ptr, int res)
{
srb_t *sp = ptr;
struct srb_iocb *lio = &sp->u.iocb_cmd;
sp->fcport->flags &= ~(FCF_ASYNC_SENT | FCF_ASYNC_ACTIVE);
if (!test_bit(UNLOADING, &sp->vha->dpc_flags))
qla2x00_post_async_logout_done_work(sp->vha, sp->fcport,
lio->u.logio.data);
sp->fcport->login_gen++;
qlt_logo_completion_handler(sp->fcport, res);
sp->free(sp);
}