From: Duoming Zhou duoming@zju.edu.cn
[ Upstream commit 2568a7e0832ee30b0a351016d03062ab4e0e0a3f ]
The l1oip_cleanup() traverses the l1oip_ilist and calls release_card() to cleanup module and stack. However, release_card() calls del_timer() to delete the timers such as keep_tl and timeout_tl. If the timer handler is running, the del_timer() will not stop it and result in UAF bugs. One of the processes is shown below:
(cleanup routine) | (timer handler) release_card() | l1oip_timeout() ... | del_timer() | ... ... | kfree(hc) //FREE | | hc->timeout_on = 0 //USE
Fix by calling del_timer_sync() in release_card(), which makes sure the timer handlers have finished before the resources, such as l1oip and so on, have been deallocated.
What's more, the hc->workq and hc->socket_thread can kick those timers right back in. We add a bool flag to show if card is released. Then, check this flag in hc->workq and hc->socket_thread.
Fixes: 3712b42d4b1b ("Add layer1 over IP support") Signed-off-by: Duoming Zhou duoming@zju.edu.cn Reviewed-by: Leon Romanovsky leonro@nvidia.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/isdn/mISDN/l1oip.h | 1 + drivers/isdn/mISDN/l1oip_core.c | 13 +++++++------ 2 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/isdn/mISDN/l1oip.h b/drivers/isdn/mISDN/l1oip.h index 7ea10db20e3a..48133d022812 100644 --- a/drivers/isdn/mISDN/l1oip.h +++ b/drivers/isdn/mISDN/l1oip.h @@ -59,6 +59,7 @@ struct l1oip { int bundle; /* bundle channels in one frm */ int codec; /* codec to use for transmis. */ int limit; /* limit number of bchannels */ + bool shutdown; /* if card is released */
/* timer */ struct timer_list keep_tl; diff --git a/drivers/isdn/mISDN/l1oip_core.c b/drivers/isdn/mISDN/l1oip_core.c index b57dcb834594..aec4f2a69c3b 100644 --- a/drivers/isdn/mISDN/l1oip_core.c +++ b/drivers/isdn/mISDN/l1oip_core.c @@ -275,7 +275,7 @@ l1oip_socket_send(struct l1oip *hc, u8 localcodec, u8 channel, u32 chanmask, p = frame;
/* restart timer */ - if (time_before(hc->keep_tl.expires, jiffies + 5 * HZ)) + if (time_before(hc->keep_tl.expires, jiffies + 5 * HZ) && !hc->shutdown) mod_timer(&hc->keep_tl, jiffies + L1OIP_KEEPALIVE * HZ); else hc->keep_tl.expires = jiffies + L1OIP_KEEPALIVE * HZ; @@ -601,7 +601,9 @@ l1oip_socket_parse(struct l1oip *hc, struct sockaddr_in *sin, u8 *buf, int len) goto multiframe;
/* restart timer */ - if (time_before(hc->timeout_tl.expires, jiffies + 5 * HZ) || !hc->timeout_on) { + if ((time_before(hc->timeout_tl.expires, jiffies + 5 * HZ) || + !hc->timeout_on) && + !hc->shutdown) { hc->timeout_on = 1; mod_timer(&hc->timeout_tl, jiffies + L1OIP_TIMEOUT * HZ); } else /* only adjust timer */ @@ -1232,11 +1234,10 @@ release_card(struct l1oip *hc) { int ch;
- if (timer_pending(&hc->keep_tl)) - del_timer(&hc->keep_tl); + hc->shutdown = true;
- if (timer_pending(&hc->timeout_tl)) - del_timer(&hc->timeout_tl); + del_timer_sync(&hc->keep_tl); + del_timer_sync(&hc->timeout_tl);
cancel_work_sync(&hc->workq);