CVSS3
Attack Vector
LOCAL
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS
Percentile
5.1%
In the Linux kernel, the following vulnerability has been resolved:
sched/fair: Fix fault in reweight_entity
Syzbot found a GPF in reweight_entity. This has been bisected to
commit 4ef0c5c6b5ba (โkernel/sched: Fix sched_fork() access an invalid
sched_task_groupโ)
Thereย is a race between sched_post_fork() and setpriority(PRIO_PGRP)
within a thread group that causes a null-ptr-derefย in
reweight_entity() in CFS. The scenario is that the main process spawns
number of new threads, which then call setpriority(PRIO_PGRP, 0, -20),
wait, and exit. For each of the new threads the copy_process() gets
invoked, which adds the new task_struct and calls sched_post_fork()
for it.
In the above scenario there is a possibility that
setpriority(PRIO_PGRP) and set_one_prio() will be called for a thread
in the group that is just being created by copy_process(), and for
which the sched_post_fork() has not been executed yet. This will
trigger a null pointer dereference in reweight_entity(),ย as it will
try to access the run queue pointer, which hasnโt been set.
Before the mentioned change the cfs_rq pointer for the task has been
set in sched_fork(), which is called much earlier in copy_process(),
before the new task is added to the thread_group. Now it is done in
the sched_post_fork(), which is called after that. To fix the issue
the remove the update_load param from the update_load param() function
and call reweight_task() only if the task flag doesnโt have the
TASK_NEW flag set.
Vendor | Product | Version | CPE |
---|---|---|---|
linux | linux_kernel | * | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
linux | linux_kernel | 5.17 | cpe:2.3:o:linux:linux_kernel:5.17:rc1:*:*:*:*:*:* |
linux | linux_kernel | 5.17 | cpe:2.3:o:linux:linux_kernel:5.17:rc2:*:*:*:*:*:* |
linux | linux_kernel | 5.17 | cpe:2.3:o:linux:linux_kernel:5.17:rc3:*:*:*:*:*:* |