In the Linux kernel, the following vulnerability has been resolved:
ALSA: Fix deadlocks with kctl removals at disconnection
In snd_card_disconnect(), we set card->shutdown flag at the beginning,
call callbacks and do sync for card->power_ref_sleep waiters at the
end. The callback may delete a kctl element, and this can lead to a
deadlock when the device was in the suspended state. Namely:
* A process waits for the power up at snd_power_ref_and_wait() in
snd_ctl_info() or read/write() inside card->controls_rwsem.
* The system gets disconnected meanwhile, and the driver tries to
delete a kctl via snd_ctl_remove*(); it tries to take
card->controls_rwsem again, but this is already locked by the
above. Since the sleeper isn't woken up, this deadlocks.
An easy fix is to wake up sleepers before processing the driver
disconnect callbacks but right after setting the card->shutdown flag.
Then all sleepers will abort immediately, and the code flows again.
So, basically this patch moves the wait_event() call at the right
timing. While we're at it, just to be sure, call wait_event_all()
instead of wait_event(), although we don't use exclusive events on
this queue for now.
In the Linux kernel, the following vulnerability has been resolved:
epoll: be better about file lifetimes
epoll can call out to vfs_poll() with a file pointer that may race with
the last 'fput()'. That would make f_count go down to zero, and while
the ep->mtx locking means that the resulting file pointer tear-down will
be blocked until the poll returns, it means that f_count is already
dead, and any use of it won't actually get a reference to the file any
more: it's dead regardless.
Make sure we have a valid ref on the file pointer before we call down to
vfs_poll() from the epoll routines.
In the Linux kernel, the following vulnerability has been resolved:
nilfs2: fix potential hang in nilfs_detach_log_writer()
Syzbot has reported a potential hang in nilfs_detach_log_writer() called
during nilfs2 unmount.
Analysis revealed that this is because nilfs_segctor_sync(), which
synchronizes with the log writer thread, can be called after
nilfs_segctor_destroy() terminates that thread, as shown in the call trace
below:
nilfs_detach_log_writer
nilfs_segctor_destroy
nilfs_segctor_kill_thread --> Shut down log writer thread
flush_work
nilfs_iput_work_func
nilfs_dispose_list
iput
nilfs_evict_inode
nilfs_transaction_commit
nilfs_construct_segment (if inode needs sync)
nilfs_segctor_sync --> Attempt to synchronize with
log writer thread
*** DEADLOCK ***
Fix this issue by changing nilfs_segctor_sync() so that the log writer
thread returns normally without synchronizing after it terminates, and by
forcing tasks that are already waiting to complete once after the thread
terminates.
The skipped inode metadata flushout will then be processed together in the
subsequent cleanup work in nilfs_segctor_destroy().
In the Linux kernel, the following vulnerability has been resolved:
nilfs2: fix use-after-free of timer for log writer thread
Patch series "nilfs2: fix log writer related issues".
This bug fix series covers three nilfs2 log writer-related issues,
including a timer use-after-free issue and potential deadlock issue on
unmount, and a potential freeze issue in event synchronization found
during their analysis. Details are described in each commit log.
This patch (of 3):
A use-after-free issue has been reported regarding the timer sc_timer on
the nilfs_sc_info structure.
The problem is that even though it is used to wake up a sleeping log
writer thread, sc_timer is not shut down until the nilfs_sc_info structure
is about to be freed, and is used regardless of the thread's lifetime.
Fix this issue by limiting the use of sc_timer only while the log writer
thread is alive.
In the Linux kernel, the following vulnerability has been resolved:
ftrace: Fix possible use-after-free issue in ftrace_location()
KASAN reports a bug:
BUG: KASAN: use-after-free in ftrace_location+0x90/0x120
Read of size 8 at addr ffff888141d40010 by task insmod/424
CPU: 8 PID: 424 Comm: insmod Tainted: G W 6.9.0-rc2+
[...]
Call Trace:
<TASK>
dump_stack_lvl+0x68/0xa0
print_report+0xcf/0x610
kasan_report+0xb5/0xe0
ftrace_location+0x90/0x120
register_kprobe+0x14b/0xa40
kprobe_init+0x2d/0xff0 [kprobe_example]
do_one_initcall+0x8f/0x2d0
do_init_module+0x13a/0x3c0
load_module+0x3082/0x33d0
init_module_from_file+0xd2/0x130
__x64_sys_finit_module+0x306/0x440
do_syscall_64+0x68/0x140
entry_SYSCALL_64_after_hwframe+0x71/0x79
The root cause is that, in lookup_rec(), ftrace record of some address
is being searched in ftrace pages of some module, but those ftrace pages
at the same time is being freed in ftrace_release_mod() as the
corresponding module is being deleted:
CPU1 | CPU2
register_kprobes() { | delete_module() {
check_kprobe_address_safe() { |
arch_check_ftrace_location() { |
ftrace_location() { |
lookup_rec() // USE! | ftrace_release_mod() // Free!
To fix this issue:
1. Hold rcu lock as accessing ftrace pages in ftrace_location_range();
2. Use ftrace_location_range() instead of lookup_rec() in
ftrace_location();
3. Call synchronize_rcu() before freeing any ftrace pages both in
ftrace_process_locs()/ftrace_release_mod()/ftrace_free_mem().
In the Linux kernel, the following vulnerability has been resolved:
gfs2: Fix potential glock use-after-free on unmount
When a DLM lockspace is released and there ares still locks in that
lockspace, DLM will unlock those locks automatically. Commit
fb6791d100d1b started exploiting this behavior to speed up filesystem
unmount: gfs2 would simply free glocks it didn't want to unlock and then
release the lockspace. This didn't take the bast callbacks for
asynchronous lock contention notifications into account, which remain
active until until a lock is unlocked or its lockspace is released.
To prevent those callbacks from accessing deallocated objects, put the
glocks that should not be unlocked on the sd_dead_glocks list, release
the lockspace, and only then free those glocks.
As an additional measure, ignore unexpected ast and bast callbacks if
the receiving glock is dead.
In the Linux kernel, the following vulnerability has been resolved:
wifi: ar5523: enable proper endpoint verification
Syzkaller reports [1] hitting a warning about an endpoint in use
not having an expected type to it.
Fix the issue by checking for the existence of all proper
endpoints with their according types intact.
Sadly, this patch has not been tested on real hardware.
[1] Syzkaller report:
------------[ cut here ]------------
usb 1-1: BOGUS urb xfer, pipe 3 != type 1
WARNING: CPU: 0 PID: 3643 at drivers/usb/core/urb.c:504 usb_submit_urb+0xed6/0x1880 drivers/usb/core/urb.c:504
...
Call Trace:
<TASK>
ar5523_cmd+0x41b/0x780 drivers/net/wireless/ath/ar5523/ar5523.c:275
ar5523_cmd_read drivers/net/wireless/ath/ar5523/ar5523.c:302 [inline]
ar5523_host_available drivers/net/wireless/ath/ar5523/ar5523.c:1376 [inline]
ar5523_probe+0x14b0/0x1d10 drivers/net/wireless/ath/ar5523/ar5523.c:1655
usb_probe_interface+0x30f/0x7f0 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:560 [inline]
really_probe+0x249/0xb90 drivers/base/dd.c:639
__driver_probe_device+0x1df/0x4d0 drivers/base/dd.c:778
driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:808
__device_attach_driver+0x1d4/0x2e0 drivers/base/dd.c:936
bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:427
__device_attach+0x1e4/0x530 drivers/base/dd.c:1008
bus_probe_device+0x1e8/0x2a0 drivers/base/bus.c:487
device_add+0xbd9/0x1e90 drivers/base/core.c:3517
usb_set_configuration+0x101d/0x1900 drivers/usb/core/message.c:2170
usb_generic_driver_probe+0xbe/0x100 drivers/usb/core/generic.c:238
usb_probe_device+0xd8/0x2c0 drivers/usb/core/driver.c:293
call_driver_probe drivers/base/dd.c:560 [inline]
really_probe+0x249/0xb90 drivers/base/dd.c:639
__driver_probe_device+0x1df/0x4d0 drivers/base/dd.c:778
driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:808
__device_attach_driver+0x1d4/0x2e0 drivers/base/dd.c:936
bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:427
__device_attach+0x1e4/0x530 drivers/base/dd.c:1008
bus_probe_device+0x1e8/0x2a0 drivers/base/bus.c:487
device_add+0xbd9/0x1e90 drivers/base/core.c:3517
usb_new_device.cold+0x685/0x10ad drivers/usb/core/hub.c:2573
hub_port_connect drivers/usb/core/hub.c:5353 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5497 [inline]
port_event drivers/usb/core/hub.c:5653 [inline]
hub_event+0x26cb/0x45d0 drivers/usb/core/hub.c:5735
process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
worker_thread+0x669/0x1090 kernel/workqueue.c:2436
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>
In the Linux kernel, the following vulnerability has been resolved:
wifi: carl9170: add a proper sanity check for endpoints
Syzkaller reports [1] hitting a warning which is caused by presence
of a wrong endpoint type at the URB sumbitting stage. While there
was a check for a specific 4th endpoint, since it can switch types
between bulk and interrupt, other endpoints are trusted implicitly.
Similar warning is triggered in a couple of other syzbot issues [2].
Fix the issue by doing a comprehensive check of all endpoints
taking into account difference between high- and full-speed
configuration.
[1] Syzkaller report:
...
WARNING: CPU: 0 PID: 4721 at drivers/usb/core/urb.c:504 usb_submit_urb+0xed6/0x1880 drivers/usb/core/urb.c:504
...
Call Trace:
<TASK>
carl9170_usb_send_rx_irq_urb+0x273/0x340 drivers/net/wireless/ath/carl9170/usb.c:504
carl9170_usb_init_device drivers/net/wireless/ath/carl9170/usb.c:939 [inline]
carl9170_usb_firmware_finish drivers/net/wireless/ath/carl9170/usb.c:999 [inline]
carl9170_usb_firmware_step2+0x175/0x240 drivers/net/wireless/ath/carl9170/usb.c:1028
request_firmware_work_func+0x130/0x240 drivers/base/firmware_loader/main.c:1107
process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
worker_thread+0x669/0x1090 kernel/workqueue.c:2436
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>
[2] Related syzkaller crashes:
In the Linux kernel, the following vulnerability has been resolved:
net: fec: remove .ndo_poll_controller to avoid deadlocks
There is a deadlock issue found in sungem driver, please refer to the
commit ac0a230f719b ("eth: sungem: remove .ndo_poll_controller to avoid
deadlocks"). The root cause of the issue is that netpoll is in atomic
context and disable_irq() is called by .ndo_poll_controller interface
of sungem driver, however, disable_irq() might sleep. After analyzing
the implementation of fec_poll_controller(), the fec driver should have
the same issue. Due to the fec driver uses NAPI for TX completions, the
.ndo_poll_controller is unnecessary to be implemented in the fec driver,
so fec_poll_controller() can be safely removed.