CVE-2025-38255 — lib/group_cpus: fix NULL pointer dereference from group_cpus_evenly()

Affected: Linux

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

lib/group_cpus: fix NULL pointer dereference from group_cpus_evenly()

While testing null_blk with configfs, echo 0 > poll_queues will trigger following panic:

BUG: kernel NULL pointer dereference, address: 0000000000000010 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 27 UID: 0 PID: 920 Comm: bash Not tainted 6.15.0-02023-gadbdb95c8696-dirty #1238 PREEMPT(undef) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:__bitmap_or+0x48/0x70 Call Trace: <TASK> __group_cpus_evenly+0x822/0x8c0 group_cpus_evenly+0x2d9/0x490 blk_mq_map_queues+0x1e/0x110 null_map_queues+0xc9/0x170 [null_blk] blk_mq_update_queue_map+0xdb/0x160 blk_mq_update_nr_hw_queues+0x22b/0x560 nullb_update_nr_hw_queues+0x71/0xf0 [null_blk] nullb_device_poll_queues_store+0xa4/0x130 [null_blk] configfs_write_iter+0x109/0x1d0 vfs_write+0x26e/0x6f0 ksys_write+0x79/0x180 __x64_sys_write+0x1d/0x30 x64_sys_call+0x45c4/0x45f0 do_syscall_64+0xa5/0x240 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Root cause is that numgrps is set to 0, and ZERO_SIZE_PTR is returned from kcalloc(), and later ZERO_SIZE_PTR will be deferenced.

Fix the problem by checking numgrps first in group_cpus_evenly(), and return NULL directly if numgrps is zero.

[yukuai3@huawei.com: also fix the non-SMP version]

USN-7833-1 — linux, linux-aws, linux-gcp, linux-oem-6.14, linux-oracle, linux-oracle-6.14, linux-raspi, linux-realtime vulnerabiliti…

Affected: Ubuntu:24.04:LTS: linux-oem-6.14, Ubuntu:24.04:LTS: linux-oracle-6.14

Oleksii Oleksenko, Cedric Fournet, Jana Hofmann, Boris Köpf, Stavros Volos, and Flavien Solt discovered that some AMD processors may allow an attacker to infer data from previous stores, potentially resulting in the leakage of privileged information. A local attacker could possibly use this to expose sensitive information. (CVE-2024-36350, CVE-2024-36357)

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM64 architecture; - PowerPC architecture; - RISC-V architecture; - S390 architecture; - x86 architecture; - ACPI drivers; - Serial ATA and Parallel ATA drivers; - Drivers core; - ATA over ethernet (AOE) driver; - Ublk userspace block driver; - Bus devices; - DMA engine subsystem; - Arm Firmware Framework for ARMv8-A(FFA); - Cirrus firmware drivers; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - I2C subsystem; - InfiniBand drivers; - Input Device (Miscellaneous) drivers; - Multiple devices driver; - Media drivers; - TI TPS6594 PFSM driver; - MMC subsystem; - MTD block device drivers; - Network drivers; - NVME drivers; - x86 platform drivers; - RapidIO drivers; - Voltage and Current Regulator drivers; - Remote Processor subsystem; - S/390 drivers; - SCSI subsystem; - TCM subsystem; - Trusted Execution Environment drivers; - TTY drivers; - ChipIdea USB dr…

Most recent entries from all

CVE-2025-38255 — lib/group_cpus: fix NULL pointer dereference from group_cpus_evenly()

USN-7833-1 — linux, linux-aws, linux-gcp, linux-oem-6.14, linux-oracle, linux-oracle-6.14, linux-raspi, linux-realtime vulnerabiliti…