Description (CNA)
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 ("kernel/sched: Fix sched_fork() access an invalid sched_task_group") There is a race between sched_post_fork() and setpriority(PRIO_PGRP) within a thread group that causes a null-ptr-deref 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(), as it will try to access the run queue pointer, which hasn't 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 doesn't have the TASK_NEW flag set.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected c85c6fadbef0a3eab41540ea628fa8fe8928c820 before 8f317cd888059c59e2fa924bf4b0957cfa53f78e; affected 3869eecf050416a1d19bac60926f6b5d64b0aa58 before e0bcd6b5779352aed88f2e538a82a39f1a7715bb; affected 4ef0c5c6b5ba1f38f0ea1cedad0cad722f00c14a before 589a954daab5e18399860b6c8ffaeaf79844eb20; affected 4ef0c5c6b5ba1f38f0ea1cedad0cad722f00c14a before 13765de8148f71fa795e0a6607de37c49ea5915a; affected 25d40b828fb855ee62e1039c65a666c9afd60786; affected 5.10.80 before 5.10.137; affected 5.15.3 before 5.15.27; affected 5.14.19 before 5.15 |
| Linux / Linux | affected 5.16; unaffected 0 before 5.16; unaffected 5.10.137 through 5.10.*; unaffected 5.15.27 through 5.15.*; unaffected 5.16.13 through 5.16.*; unaffected 5.17 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/8f317cd888059c59e2fa924bf4b0957cfa53f78e
- https://git.kernel.org/stable/c/e0bcd6b5779352aed88f2e538a82a39f1a7715bb
- https://git.kernel.org/stable/c/589a954daab5e18399860b6c8ffaeaf79844eb20
- https://git.kernel.org/stable/c/13765de8148f71fa795e0a6607de37c49ea5915a
ADP enrichment
No English description supplied.
No references supplied.