In the Linux kernel, the following vulnerability has been resolved:
Input: powermate - fix use-after-free in powermate_config_complete
syzbot has found a use-after-free bug [1] in the powermate driver. This
happens when the device is disconnected, which leads to a memory free from
the powermate_device struct. When an asynchronous control message
completes after the kfree and its callback is invoked, the lock does not
exist anymore and hence the bug.
Use usb_kill_urb() on pm->config to cancel any in-progress requests upon
device disconnection.
[1] https://syzkaller.appspot.com/bug?extid=0434ac83f907a1dbdd1e
In the Linux kernel, the following vulnerability has been resolved:
perf/x86/lbr: Filter vsyscall addresses
We found that a panic can occur when a vsyscall is made while LBR sampling
is active. If the vsyscall is interrupted (NMI) for perf sampling, this
call sequence can occur (most recent at top):
__insn_get_emulate_prefix()
insn_get_emulate_prefix()
insn_get_prefixes()
insn_get_opcode()
decode_branch_type()
get_branch_type()
intel_pmu_lbr_filter()
intel_pmu_handle_irq()
perf_event_nmi_handler()
Within __insn_get_emulate_prefix() at frame 0, a macro is called:
peek_nbyte_next(insn_byte_t, insn, i)
Within this macro, this dereference occurs:
(insn)->next_byte
Inspecting registers at this point, the value of the next_byte field is the
address of the vsyscall made, for example the location of the vsyscall
version of gettimeofday() at 0xffffffffff600000. The access to an address
in the vsyscall region will trigger an oops due to an unhandled page fault.
To fix the bug, filtering for vsyscalls can be done when
determining the branch type. This patch will return
a "none" branch if a kernel address if found to lie in the
vsyscall region.
In the Linux kernel, the following vulnerability has been resolved:
HID: logitech-hidpp: Fix kernel crash on receiver USB disconnect
hidpp_connect_event() has *four* time-of-check vs time-of-use (TOCTOU)
races when it races with itself.
hidpp_connect_event() primarily runs from a workqueue but it also runs
on probe() and if a "device-connected" packet is received by the hw
when the thread running hidpp_connect_event() from probe() is waiting on
the hw, then a second thread running hidpp_connect_event() will be
started from the workqueue.
This opens the following races (note the below code is simplified):
1. Retrieving + printing the protocol (harmless race):
if (!hidpp->protocol_major) {
hidpp_root_get_protocol_version()
hidpp->protocol_major = response.rap.params[0];
}
We can actually see this race hit in the dmesg in the abrt output
attached to rhbz#2227968:
[ 3064.624215] logitech-hidpp-device 0003:046D:4071.0049: HID++ 4.5 device connected.
[ 3064.658184] logitech-hidpp-device 0003:046D:4071.0049: HID++ 4.5 device connected.
Testing with extra logging added has shown that after this the 2 threads
take turn grabbing the hw access mutex (send_mutex) so they ping-pong
through all the other TOCTOU cases managing to hit all of them:
2. Updating the name to the HIDPP name (harmless race):
if (hidpp->name == hdev->name) {
...
hidpp->name = new_name;
}
3. Initializing the power_supply class for the battery (problematic!):
hidpp_initialize_battery()
{
if (hidpp->battery.ps)
return 0;
probe_battery(); /* Blocks, threads take turns executing this */
hidpp->battery.desc.properties =
devm_kmemdup(dev, hidpp_battery_props, cnt, GFP_KERNEL);
hidpp->battery.ps =
devm_power_supply_register(&hidpp->hid_dev->dev,
&hidpp->battery.desc, cfg);
}
4. Creating delayed input_device (potentially problematic):
if (hidpp->delayed_input)
return;
hidpp->delayed_input = hidpp_allocate_input(hdev);
The really big problem here is 3. Hitting the race leads to the following
sequence:
hidpp->battery.desc.properties =
devm_kmemdup(dev, hidpp_battery_props, cnt, GFP_KERNEL);
hidpp->battery.ps =
devm_power_supply_register(&hidpp->hid_dev->dev,
&hidpp->battery.desc, cfg);
...
hidpp->battery.desc.properties =
devm_kmemdup(dev, hidpp_battery_props, cnt, GFP_KERNEL);
hidpp->battery.ps =
devm_power_supply_register(&hidpp->hid_dev->dev,
&hidpp->battery.desc, cfg);
So now we have registered 2 power supplies for the same battery,
which looks a bit weird from userspace's pov but this is not even
the really big problem.
Notice how:
1. This is all devm-maganaged
2. The hidpp->battery.desc struct is shared between the 2 power supplies
3. hidpp->battery.desc.properties points to the result from the second
devm_kmemdup()
This causes a use after free scenario on USB disconnect of the receiver:
1. The last registered power supply class device gets unregistered
2. The memory from the last devm_kmemdup() call gets freed,
hidpp->battery.desc.properties now points to freed memory
3. The first registered power supply class device gets unregistered,
this involves sending a remove uevent to userspace which invokes
power_supply_uevent() to fill the uevent data
4. power_supply_uevent() uses hidpp->battery.desc.properties which
now points to freed memory leading to backtraces like this one:
Sep 22 20:01:35 eric kernel: BUG: unable to handle page fault for address: ffffb2140e017f08
...
Sep 22 20:01:35 eric kernel: Workqueue: usb_hub_wq hub_event
Sep 22 20:01:35 eric kernel: RIP: 0010:power_supply_uevent+0xee/0x1d0
...
Sep 22 20:01:35 eric kernel: ? asm_exc_page_fault+0x26/0x30
Sep 22 20:01:35 eric kernel: ? power_supply_uevent+0xee/0x1d0
Sep 22 20:01:35 eric kernel: ? power_supply_uevent+0x10d/0x1d0
Sep 22 20:01:35 eric kernel: dev_uevent+0x10f/0x2d0
Sep 22 20:01:35 eric kernel: kobject_uevent_env+0x291/0x680
Sep 22 20:01:35 eric kernel:
---truncated---
In the Linux kernel, the following vulnerability has been resolved:
SUNRPC: Fix null pointer dereference in svc_rqst_free()
When alloc_pages_node() returns null in svc_rqst_alloc(), the
null rq_scratch_page pointer will be dereferenced when calling
put_page() in svc_rqst_free(). Fix it by adding a null check.
Addresses-Coverity: ("Dereference after null check")
In the Linux kernel, the following vulnerability has been resolved:
ALSA: hda: intel-sdw-acpi: harden detection of controller
The existing code currently sets a pointer to an ACPI handle before
checking that it's actually a SoundWire controller. This can lead to
issues where the graph walk continues and eventually fails, but the
pointer was set already.
This patch changes the logic so that the information provided to
the caller is set when a controller is found.
In the Linux kernel, the following vulnerability has been resolved:
parisc: Clear stale IIR value on instruction access rights trap
When a trap 7 (Instruction access rights) occurs, this means the CPU
couldn't execute an instruction due to missing execute permissions on
the memory region. In this case it seems the CPU didn't even fetched
the instruction from memory and thus did not store it in the cr19 (IIR)
register before calling the trap handler. So, the trap handler will find
some random old stale value in cr19.
This patch simply overwrites the stale IIR value with a constant magic
"bad food" value (0xbaadf00d), in the hope people don't start to try to
understand the various random IIR values in trap 7 dumps.
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to avoid potential deadlock
Using f2fs_trylock_op() in f2fs_write_compressed_pages() to avoid potential
deadlock like we did in f2fs_write_single_data_page().
In the Linux kernel, the following vulnerability has been resolved:
HID: usbhid: fix info leak in hid_submit_ctrl
In hid_submit_ctrl(), the way of calculating the report length doesn't
take into account that report->size can be zero. When running the
syzkaller reproducer, a report of size 0 causes hid_submit_ctrl) to
calculate transfer_buffer_length as 16384. When this urb is passed to
the usb core layer, KMSAN reports an info leak of 16384 bytes.
To fix this, first modify hid_report_len() to account for the zero
report size case by using DIV_ROUND_UP for the division. Then, call it
from hid_submit_ctrl().