diff options
| author | Yi Yang <yiyang13@huawei.com> | 2023-08-11 11:11:21 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-08-11 21:17:02 +0200 |
| commit | 3c4f8333b582487a2d1e02171f1465531cde53e3 (patch) | |
| tree | eee7ae7841250c0ebc81c6c08ee79d7f4ac4e555 /drivers/tty | |
| parent | a4a79e03bab57729bd8046d22bf3666912e586fb (diff) | |
tty: n_gsm: fix the UAF caused by race condition in gsm_cleanup_mux
In commit 9b9c8195f3f0 ("tty: n_gsm: fix UAF in gsm_cleanup_mux"), the UAF
problem is not completely fixed. There is a race condition in
gsm_cleanup_mux(), which caused this UAF.
The UAF problem is triggered by the following race:
task[5046] task[5054]
----------------------- -----------------------
gsm_cleanup_mux();
dlci = gsm->dlci[0];
mutex_lock(&gsm->mutex);
gsm_cleanup_mux();
dlci = gsm->dlci[0]; //Didn't take the lock
gsm_dlci_release(gsm->dlci[i]);
gsm->dlci[i] = NULL;
mutex_unlock(&gsm->mutex);
mutex_lock(&gsm->mutex);
dlci->dead = true; //UAF
Fix it by assigning values after mutex_lock().
Link: https://syzkaller.appspot.com/text?tag=CrashReport&x=176188b5a80000
Cc: stable <stable@kernel.org>
Fixes: 9b9c8195f3f0 ("tty: n_gsm: fix UAF in gsm_cleanup_mux")
Fixes: aa371e96f05d ("tty: n_gsm: fix restart handling via CLD command")
Signed-off-by: Yi Yang <yiyang13@huawei.com>
Co-developed-by: Qiumiao Zhang <zhangqiumiao1@huawei.com>
Signed-off-by: Qiumiao Zhang <zhangqiumiao1@huawei.com>
Link: https://lore.kernel.org/r/20230811031121.153237-1-yiyang13@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/n_gsm.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 1cdefac4dd1b..739f522cb893 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -3042,12 +3042,13 @@ static void gsm_error(struct gsm_mux *gsm) static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc) { int i; - struct gsm_dlci *dlci = gsm->dlci[0]; + struct gsm_dlci *dlci; struct gsm_msg *txq, *ntxq; gsm->dead = true; mutex_lock(&gsm->mutex); + dlci = gsm->dlci[0]; if (dlci) { if (disc && dlci->state != DLCI_CLOSED) { gsm_dlci_begin_close(dlci); |