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Vulnerability · Published Jul 9, 2025 · Assigned by Linux

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

Medium 5.5

In plain English

A medium-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)5.5Medium
Exploit odds (30 days)0.2%top 94.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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]

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:13linux6.12.37-1DEBIAN-CVE-2025-38255
Debian:14linux6.12.37-1DEBIAN-CVE-2025-38255
Ubuntu:24.04:LTSlinux6.8.0-100.100UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-aws6.8.0-1046.49UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-aws-6.146.14.0-1015.15~24.04.1UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-aws-6.86.8.0-1046.49~22.04.1UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-azure6.8.0-1046.52UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-azure-6.146.14.0-1014.14~24.04.1UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-azure-6.86.8.0-1051.57~22.04.1UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-azure-fde6.8.0-1046.53UBUNTU-CVE-2025-38255
Ubuntu:25.10linux-azure-fdeno fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-azure-fde-6.86.8.0-1046.53~22.04.1UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-azure-nvidia-6.146.14.0-1007.7UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-gcp6.8.0-1047.50UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-gcp-6.146.14.0-1018.19~24.04.1UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-gcp-6.86.8.0-1047.50~22.04.2UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-gke6.8.0-1043.48UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-gkeop6.8.0-1030.33UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-hwe-6.86.8.0-100.100~22.04.1UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-ibm6.8.0-1044.44UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-ibm-6.86.8.0-1044.44~22.04.1UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-intelno fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-lowlatency6.8.0-100.100.1UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.86.8.0-100.100.1~22.04.1UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-nvidia6.8.0-1046.49UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-nvidia-6.86.8.0-1046.49~22.04.1UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-nvidia-lowlatency6.8.0-1046.49.1UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-nvidia-tegra6.8.0-1020.20UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-oem-6.146.14.0-1014.14UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-oracle6.8.0-1043.44UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-oracle-6.146.14.0-1015.15~24.04.1UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-oracle-6.86.8.0-1043.44~22.04.1UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-raspi6.8.0-1047.51UBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-riscv-6.146.14.0-34.34.1~24.04.1UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-riscv-6.86.8.0-100.100~22.04.1UBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2025-38255
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2025-38255
Ubuntu:24.04:LTSlinux-xilinx6.8.0-1023.24UBUNTU-CVE-2025-38255

Affected products (as reported)

VendorProductVersions
Linux Linux 6a6dcae8f486c3f3298d0767d34505121c7b0b81 – before 64a99eff8dcf1f951a544e6058341b2b19a8fdbd6a6dcae8f486c3f3298d0767d34505121c7b0b81 – before 29d39e0d5f16c060e32542b2cf351c09fd22b2506a6dcae8f486c3f3298d0767d34505121c7b0b81 – before 911ef2e8a7de5b2bae8ff11fb0bd01f699e6db656a6dcae8f486c3f3298d0767d34505121c7b0b81 – before df831e97739405ecbaddb85516bc7d4d1c933d6b
Linux Linux 6.3

References