MEDIUM5.5
In the Linux kernel, the following vulnerability has been resolved:
powerpc/hv-gpci: fix preempt count leak in sysfs show paths
Four sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb)
(which calls preempt_disable()) but only call the matching put_cpu_var()
on the error path under the 'out:' label. Every successful read leaks
one preempt_disable():
processor_bus_topology_show()
processor_config_show()
affinity_domain_via_virtual_processor_show()
affinity_domain_via_domain_show()
(affinity_domain_via_partition_show() was already correct.)
On a CONFIG_PREEMPT=y kernel, repeated reads raise preempt_count and
eventually return to userspace with preemption still disabled. The
next user-mode page fault then hits faulthandler_disabled() == 1,
gets forced to SIGSEGV, and the resulting coredump trips
'BUG: scheduling while atomic' in call_usermodehelper_exec ->
wait_for_completion_state -> schedule:
BUG: scheduling while atomic: //0x00000004
...
__schedule_bug+0x6c/0x90
__schedule+0x58c/0x13a0
schedule+0x48/0x1a0
schedule_timeout+0x104/0x170
wait_for_completion_state+0x16c/0x330
call_usermodehelper_exec+0x254/0x2d0
vfs_coredump+0x1050/0x2590
get_signal+0xb9c/0xc80
do_notify_resume+0xf8/0x470
Add an out_success label that calls put_cpu_var() before returning
the byte count, mirroring affinity_domain_via_partition_show().
CVSS 3.xСРЕДНЯЯ 5.5
CVSS:3.x/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HСсылки
- https://git.kernel.org/stable/c/45afabe7f99c5d8746434ee41c86584c01d70147
- https://git.kernel.org/stable/c/903409000a07ac8e31ffedeb8516f4f8d67150c8
- https://git.kernel.org/stable/c/b300312562fd6e4729697adb9f777f00ca0429f3
- https://git.kernel.org/stable/c/b61ebb2826ca1852c2bbd92a676fb622c358cab4
- https://git.kernel.org/stable/c/dbc30a57bd8e026995e9fa8e8c31cffd18542c01