CVE-2024-49926

rcu-tasks: Fix access non-existent percpu rtpcp variable in rcu_tasks_need_gpcb()

State: Published
Severity: Not scored
Published: Oct 21, 2024
Updated: Oct 30, 2026
Reserved: Oct 21, 2024

Description

In the Linux kernel, the following vulnerability has been resolved:

rcu-tasks: Fix access non-existent percpu rtpcp variable in rcu_tasks_need_gpcb()

For kernels built with CONFIG_FORCE_NR_CPUS=y, the nr_cpu_ids is defined as NR_CPUS instead of the number of possible cpus, this will cause the following system panic:

smpboot: Allowing 4 CPUs, 0 hotplug CPUs ... setup_percpu: NR_CPUS:512 nr_cpumask_bits:512 nr_cpu_ids:512 nr_node_ids:1 ... BUG: unable to handle page fault for address: ffffffff9911c8c8 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 15 Comm: rcu_tasks_trace Tainted: G W 6.6.21 #1 5dc7acf91a5e8e9ac9dcfc35bee0245691283ea6 RIP: 0010:rcu_tasks_need_gpcb+0x25d/0x2c0 RSP: 0018:ffffa371c00a3e60 EFLAGS: 00010082 CR2: ffffffff9911c8c8 CR3: 000000040fa20005 CR4: 00000000001706f0 Call Trace: <TASK> ? __die+0x23/0x80 ? page_fault_oops+0xa4/0x180 ? exc_page_fault+0x152/0x180 ? asm_exc_page_fault+0x26/0x40 ? rcu_tasks_need_gpcb+0x25d/0x2c0 ? __pfx_rcu_tasks_kthread+0x40/0x40 rcu_tasks_one_gp+0x69/0x180 rcu_tasks_kthread+0x94/0xc0 kthread+0xe8/0x140 ? __pfx_kthread+0x40/0x40 ret_from_fork+0x34/0x80 ? __pfx_kthread+0x40/0x40 ret_from_fork_asm+0x1b/0x80 </TASK>

Considering that there may be holes in the CPU numbers, use the maximum possible cpu number, instead of nr_cpu_ids, for configuring enqueue and dequeue limits.

[ neeraj.upadhyay: Fix htmldocs build error reported by Stephen Rothwell ]

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	8610b65680390a103b58f46282a1b05f7eebbba4 to before a89f6e90e64ecadd19f32bb8128d22b518bd656cAffected 8610b65680390a103b58f46282a1b05f7eebbba4 to before b3b2431ed27f4ebc28e26cdf005c1de42dc60bdfAffected 8610b65680390a103b58f46282a1b05f7eebbba4 to before 3104bddc666ff64b90491868bbc4c7ebdd90aedfAffected 8610b65680390a103b58f46282a1b05f7eebbba4 to before 05095271a4fb0f6497121a057f9a2edf386d5d96Affected 8610b65680390a103b58f46282a1b05f7eebbba4 to before fd70e9f1d85f5323096ad313ba73f5fe3d15ea41Affected
LinuxLinux	5.17Affected before 5.17Not affected 6.1.191 through 6.1.Not affected 6.6.60 through 6.6.Not affected 6.10.14 through 6.10.Not affected 6.11.3 through 6.11.Not affected 6.12 and laterNot affected

Product

Versions

LinuxLinux

8610b65680390a103b58f46282a1b05f7eebbba4 to before a89f6e90e64ecadd19f32bb8128d22b518bd656cAffected
8610b65680390a103b58f46282a1b05f7eebbba4 to before b3b2431ed27f4ebc28e26cdf005c1de42dc60bdfAffected
8610b65680390a103b58f46282a1b05f7eebbba4 to before 3104bddc666ff64b90491868bbc4c7ebdd90aedfAffected
8610b65680390a103b58f46282a1b05f7eebbba4 to before 05095271a4fb0f6497121a057f9a2edf386d5d96Affected
8610b65680390a103b58f46282a1b05f7eebbba4 to before fd70e9f1d85f5323096ad313ba73f5fe3d15ea41Affected

LinuxLinux

5.17Affected
before 5.17Not affected
6.1.191 through 6.1.*Not affected
6.6.60 through 6.6.*Not affected
6.10.14 through 6.10.*Not affected
6.11.3 through 6.11.*Not affected
6.12 and laterNot affected

References

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