In the Linux kernel, the following vulnerability has been resolved:
drivers: tty: serial: Fix deadlock in sa1100_set_termios()
There is a deadlock in sa1100_set_termios(), which is shown
below:
(Thread 1) | (Thread 2)
| sa1100_enable_ms()
sa1100_set_termios() | mod_timer()
spin_lock_irqsave() //(1) | (wait a time)
... | sa1100_timeout()
del_timer_sync() | spin_lock_irqsave() //(2)
(wait timer to stop) | ...
We hold sport->port.lock in position (1) of thread 1 and
use del_timer_sync() to wait timer to stop, but timer handler
also need sport->port.lock in position (2) of thread 2. As a result,
sa1100_set_termios() will block forever.
This patch moves del_timer_sync() before spin_lock_irqsave()
in order to prevent the deadlock.
In the Linux kernel, the following vulnerability has been resolved:
drivers: staging: rtl8192u: Fix deadlock in ieee80211_beacons_stop()
There is a deadlock in ieee80211_beacons_stop(), which is shown below:
(Thread 1) | (Thread 2)
| ieee80211_send_beacon()
ieee80211_beacons_stop() | mod_timer()
spin_lock_irqsave() //(1) | (wait a time)
... | ieee80211_send_beacon_cb()
del_timer_sync() | spin_lock_irqsave() //(2)
(wait timer to stop) | ...
We hold ieee->beacon_lock in position (1) of thread 1 and use
del_timer_sync() to wait timer to stop, but timer handler
also need ieee->beacon_lock in position (2) of thread 2.
As a result, ieee80211_beacons_stop() will block forever.
This patch extracts del_timer_sync() from the protection of
spin_lock_irqsave(), which could let timer handler to obtain
the needed lock.
In the Linux kernel, the following vulnerability has been resolved:
tty: synclink_gt: Fix null-pointer-dereference in slgt_clean()
When the driver fails at alloc_hdlcdev(), and then we remove the driver
module, we will get the following splat:
[ 25.065966] general protection fault, probably for non-canonical address 0xdffffc0000000182: 0000 [#1] PREEMPT SMP KASAN PTI
[ 25.066914] KASAN: null-ptr-deref in range [0x0000000000000c10-0x0000000000000c17]
[ 25.069262] RIP: 0010:detach_hdlc_protocol+0x2a/0x3e0
[ 25.077709] Call Trace:
[ 25.077924] <TASK>
[ 25.078108] unregister_hdlc_device+0x16/0x30
[ 25.078481] slgt_cleanup+0x157/0x9f0 [synclink_gt]
Fix this by checking whether the 'info->netdev' is a null pointer first.
In the Linux kernel, the following vulnerability has been resolved:
drivers: staging: rtl8723bs: Fix deadlock in rtw_surveydone_event_callback()
There is a deadlock in rtw_surveydone_event_callback(),
which is shown below:
(Thread 1) | (Thread 2)
| _set_timer()
rtw_surveydone_event_callback()| mod_timer()
spin_lock_bh() //(1) | (wait a time)
... | rtw_scan_timeout_handler()
del_timer_sync() | spin_lock_bh() //(2)
(wait timer to stop) | ...
We hold pmlmepriv->lock in position (1) of thread 1 and use
del_timer_sync() to wait timer to stop, but timer handler
also need pmlmepriv->lock in position (2) of thread 2.
As a result, rtw_surveydone_event_callback() will block forever.
This patch extracts del_timer_sync() from the protection of
spin_lock_bh(), which could let timer handler to obtain
the needed lock. What`s more, we change spin_lock_bh() in
rtw_scan_timeout_handler() to spin_lock_irq(). Otherwise,
spin_lock_bh() will also cause deadlock() in timer handler.
In the Linux kernel, the following vulnerability has been resolved:
drivers: staging: rtl8192bs: Fix deadlock in rtw_joinbss_event_prehandle()
There is a deadlock in rtw_joinbss_event_prehandle(), which is shown
below:
(Thread 1) | (Thread 2)
| _set_timer()
rtw_joinbss_event_prehandle()| mod_timer()
spin_lock_bh() //(1) | (wait a time)
... | _rtw_join_timeout_handler()
del_timer_sync() | spin_lock_bh() //(2)
(wait timer to stop) | ...
We hold pmlmepriv->lock in position (1) of thread 1 and
use del_timer_sync() to wait timer to stop, but timer handler
also need pmlmepriv->lock in position (2) of thread 2.
As a result, rtw_joinbss_event_prehandle() will block forever.
This patch extracts del_timer_sync() from the protection of
spin_lock_bh(), which could let timer handler to obtain
the needed lock. What`s more, we change spin_lock_bh() to
spin_lock_irq() in _rtw_join_timeout_handler() in order to
prevent deadlock.
In the Linux kernel, the following vulnerability has been resolved:
staging: rtl8712: fix a potential memory leak in r871xu_drv_init()
In r871xu_drv_init(), if r8712_init_drv_sw() fails, then the memory
allocated by r8712_alloc_io_queue() in r8712_usb_dvobj_init() is not
properly released as there is no action will be performed by
r8712_usb_dvobj_deinit().
To properly release it, we should call r8712_free_io_queue() in
r8712_usb_dvobj_deinit().
Besides, in r871xu_dev_remove(), r8712_usb_dvobj_deinit() will be called
by r871x_dev_unload() under condition `padapter->bup` and
r8712_free_io_queue() is called by r8712_free_drv_sw().
However, r8712_usb_dvobj_deinit() does not rely on `padapter->bup` and
calling r8712_free_io_queue() in r8712_free_drv_sw() is negative for
better understading the code.
So I move r8712_usb_dvobj_deinit() into r871xu_dev_remove(), and remove
r8712_free_io_queue() from r8712_free_drv_sw().
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Check if modulo is 0 before dividing.
[How & Why]
If a value of 0 is read, then this will cause a divide-by-0 panic.
In the Linux kernel, the following vulnerability has been resolved:
nbd: call genl_unregister_family() first in nbd_cleanup()
Otherwise there may be race between module removal and the handling of
netlink command, which can lead to the oops as shown below:
BUG: kernel NULL pointer dereference, address: 0000000000000098
Oops: 0002 [#1] SMP PTI
CPU: 1 PID: 31299 Comm: nbd-client Tainted: G E 5.14.0-rc4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
RIP: 0010:down_write+0x1a/0x50
Call Trace:
start_creating+0x89/0x130
debugfs_create_dir+0x1b/0x130
nbd_start_device+0x13d/0x390 [nbd]
nbd_genl_connect+0x42f/0x748 [nbd]
genl_family_rcv_msg_doit.isra.0+0xec/0x150
genl_rcv_msg+0xe5/0x1e0
netlink_rcv_skb+0x55/0x100
genl_rcv+0x29/0x40
netlink_unicast+0x1a8/0x250
netlink_sendmsg+0x21b/0x430
____sys_sendmsg+0x2a4/0x2d0
___sys_sendmsg+0x81/0xc0
__sys_sendmsg+0x62/0xb0
__x64_sys_sendmsg+0x1f/0x30
do_syscall_64+0x3b/0xc0
entry_SYSCALL_64_after_hwframe+0x44/0xae
Modules linked in: nbd(E-)
In the Linux kernel, the following vulnerability has been resolved:
nbd: fix race between nbd_alloc_config() and module removal
When nbd module is being removing, nbd_alloc_config() may be
called concurrently by nbd_genl_connect(), although try_module_get()
will return false, but nbd_alloc_config() doesn't handle it.
The race may lead to the leak of nbd_config and its related
resources (e.g, recv_workq) and oops in nbd_read_stat() due
to the unload of nbd module as shown below:
BUG: kernel NULL pointer dereference, address: 0000000000000040
Oops: 0000 [#1] SMP PTI
CPU: 5 PID: 13840 Comm: kworker/u17:33 Not tainted 5.14.0+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
Workqueue: knbd16-recv recv_work [nbd]
RIP: 0010:nbd_read_stat.cold+0x130/0x1a4 [nbd]
Call Trace:
recv_work+0x3b/0xb0 [nbd]
process_one_work+0x1ed/0x390
worker_thread+0x4a/0x3d0
kthread+0x12a/0x150
ret_from_fork+0x22/0x30
Fixing it by checking the return value of try_module_get()
in nbd_alloc_config(). As nbd_alloc_config() may return ERR_PTR(-ENODEV),
assign nbd->config only when nbd_alloc_config() succeeds to ensure
the value of nbd->config is binary (valid or NULL).
Also adding a debug message to check the reference counter
of nbd_config during module removal.