CVE - CVE-2022-48921

CVE-ID
CVE-2022-48921	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
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.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/13765de8148f71fa795e0a6607de37c49ea5915a URL:https://git.kernel.org/stable/c/13765de8148f71fa795e0a6607de37c49ea5915a MISC:https://git.kernel.org/stable/c/589a954daab5e18399860b6c8ffaeaf79844eb20 URL:https://git.kernel.org/stable/c/589a954daab5e18399860b6c8ffaeaf79844eb20 MISC:https://git.kernel.org/stable/c/8f317cd888059c59e2fa924bf4b0957cfa53f78e URL:https://git.kernel.org/stable/c/8f317cd888059c59e2fa924bf4b0957cfa53f78e MISC:https://git.kernel.org/stable/c/e0bcd6b5779352aed88f2e538a82a39f1a7715bb URL:https://git.kernel.org/stable/c/e0bcd6b5779352aed88f2e538a82a39f1a7715bb
Assigning CNA
kernel.org
Date Record Created
20240821	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20240821)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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