In the Linux kernel, the following vulnerability has been resolved:
bpf: use kvfree() for replaced sysctl write buffer
proc_sys_call_handler() allocates its temporary sysctl buffer with kvzalloc() and passes it to __cgroup_bpf_run_filter_sysctl(). Since kvzalloc() may fall back to vmalloc() for large allocations, freeing that buffer with kfree() is wrong and can corrupt memory.
Use kvfree() to safely handle both kmalloc and kvzalloc()/vmalloc allocations.
The bug was first flagged by an experimental analysis tool we are developing for kernel memory-management bugs while analyzing v6.13-rc1. The tool is still under development and is not yet publicly available. Manual inspection confirms that the bug is still present in v7.1-rc5.
Reproduced the bug based on v7.1-rc4 in a QEMU x86_64 guest booted with KASAN and CONFIG_FAILSLAB enabled. To exercise the replacement path, the test tree also included the accompanying fix for the stale ret == 1 check in __cgroup_bpf_run_filter_sysctl(). The reproducer confines failslab injections to the proc_sys_call_handler() range, uses stacktrace-depth=32, and injects fail-nth=1 while writing 8191 bytes to /proc/sys/kernel/domainname from a task in the target cgroup. Under that setup, fail-nth=1 triggered the fault:
BUG: unable to handle page fault for address: ffffeb0200024d48 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 SMP KASAN NOPTI CPU: 2 UID: 0 PID: 209 Comm: repro_proc_sys_ Not tainted 7.1.0-rc4-00686-g97625979a5d4 PREEMPT(lazy) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014 RIP: 0010:kfree+0x6e/0x510 ... Call Trace: <TASK> ? __cgroup_bpf_run_filter_sysctl+0x626/0xc30 __cgroup_bpf_run_filter_sysctl+0x74d/0xc30 ? __pfx___cgroup_bpf_run_filter_sysctl+0x10/0x10 ? srso_return_thunk+0x5/0x5f ? __kvmalloc_node_noprof+0x345/0x870 ? proc_sys_call_handler+0x250/0x480 ? srso_return_thunk+0x5/0x5f proc_sys_call_handler+0x3a2/0x480 ? __pfx_proc_sys_call_handler+0x10/0x10 ? srso_return_thunk+0x5/0x5f ? selinux_file_permission+0x39f/0x500 ? srso_return_thunk+0x5/0x5f ? lock_is_held_type+0x9e/0x120 vfs_write+0x98e/0x1000 ... </TASK>
With this fix applied on top of the same test setup, rerunning the reproducer with fail-nth=1 yields no corresponding Oops reports.
CVSS Details
- CVSS 3.1 Base Score: 7.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade perf-debuginfoUpgrade kernel-toolsUpgrade kernel-livepatch-5.15.211-149.249Upgrade kernel-headersUpgrade kernel-debuginfo-common-aarch64Upgrade python-perf-debuginfoUpgrade kernel-develUpgrade kernel-tools-develUpgrade perfUpgrade kernel-debuginfo-common-x86_64Upgrade python-perfUpgrade bpftool-debuginfoUpgrade kernelUpgrade kernel-tools-debuginfoUpgrade kernel-livepatch-5.10.260-259.1053Upgrade bpftoolUpgrade kernel-debuginfo | Aug 2, 2026 | Aug 2, 2026 |
| Amazon_linux_2023 | — | Upgrade python3-perf6.12-debuginfoUpgrade kernel6.18-debuginfo-common-x86_64Upgrade microvm-kernel6.18Upgrade python3-perf6.18Upgrade kernel6.12-debuginfo-common-x86_64Upgrade kernel6.12-headersUpgrade bpftool6.18Upgrade kernel-livepatch-6.18.38-73.137Upgrade kernel6.12-tools-develUpgrade kernel6.18-modules-extra-commonUpgrade kernel6.18-tools-debuginfoUpgrade perf6.12Upgrade python3-perf6.18-debuginfoUpgrade perf6.18Upgrade kernel6.12-tools-debuginfoUpgrade kernel6.12-toolsUpgrade kernel6.12-debuginfoUpgrade kernel6.18-develUpgrade kernel6.18-tools-develUpgrade kernel6.12-modules-extraUpgrade bpftool6.12-debuginfoUpgrade perf6.18-debuginfoUpgrade kernel6.18-headersUpgrade bpftool6.18-debuginfoUpgrade kernel6.12Upgrade kernel6.18-debuginfo-common-aarch64Upgrade perf6.12-debuginfoUpgrade python3-perf6.12Upgrade kernel6.18Upgrade kernel6.12-debuginfo-common-aarch64Upgrade kernel6.18-modules-extraUpgrade bpftool6.12Upgrade kernel6.18-debuginfoUpgrade kernel6.18-toolsUpgrade kernel6.12-develUpgrade kernel-livepatch-6.12.95-124.187Upgrade kernel6.12-modules-extra-common | Aug 10, 2026 | Jul 19, 2026 |
| Debian | — | Upgrade linuxUpgrade linux-6.1 | Jul 20, 2026 | Jul 20, 2026 |
| Redhat_linux | — | No solution exists | Jul 22, 2026 | Jul 19, 2026 |
| Ubuntu | — | Upgrade linux-image-7.0.0-1013-oemUpgrade linux-image-7.0.0-1011-oracle-64kUpgrade linux-image-generic-64k-7.0Upgrade linux-image-7.0.0-1012-awsUpgrade linux-image-realtime-7.0Upgrade linux-image-realtime-hwe-26.04Upgrade linux-image-7.0.0-1019-raspi-realtimeUpgrade linux-image-virtualUpgrade linux-image-nvidia-bos-7.0Upgrade linux-image-7.0.0-31-generic-64kUpgrade linux-image-nvidia-64k-hwe-26.04Upgrade linux-image-virtual-hwe-24.04Upgrade linux-image-generic-64kUpgrade linux-image-gcp-64k-7.0Upgrade linux-image-gkeUpgrade linux-image-7.0.0-1018-nvidia-64kUpgrade linux-image-raspi-realtime-7.0Upgrade linux-image-aws-7.0Upgrade linux-image-aws-64k-7.0Upgrade linux-image-7.0.0-2018-nvidia-bosUpgrade linux-image-oracleUpgrade linux-image-nvidiaUpgrade linux-image-genericUpgrade linux-image-aws-64kUpgrade linux-image-realtime-64kUpgrade linux-image-realtimeUpgrade linux-image-7.0.0-1019-raspiUpgrade linux-image-nvidia-bosUpgrade linux-image-gke-64k-hwe-26.04Upgrade linux-image-gcp-64kUpgrade linux-image-gke-hwe-26.04Upgrade linux-image-oem-26.04aUpgrade linux-image-generic-7.0Upgrade linux-image-generic-64k-hwe-26.04Upgrade linux-image-virtual-7.0Upgrade linux-image-7.0.0-1006-gke-64kUpgrade linux-image-gke-7.0Upgrade linux-image-7.0.0-1014-azureUpgrade linux-image-nvidia-hwe-26.04Upgrade linux-image-raspi-7.0Upgrade linux-image-realtime-64k-7.0Upgrade linux-image-generic-hwe-26.04Upgrade linux-image-raspiUpgrade linux-image-7.0.0-1012-aws-64kUpgrade linux-image-oracle-64kUpgrade linux-image-oracle-64k-7.0Upgrade linux-image-gke-64k-7.0Upgrade linux-image-azure-7.0Upgrade linux-image-nvidia-7.0Upgrade linux-image-7.0.0-31-realtimeUpgrade linux-image-oem-26.04bUpgrade linux-image-generic-hwe-24.04Upgrade linux-image-nvidia-64kUpgrade linux-image-7.0.0-31-realtime-64kUpgrade linux-image-gcpUpgrade linux-image-gcp-7.0Upgrade linux-image-realtime-64k-hwe-26.04Upgrade linux-image-7.0.0-1011-gcpUpgrade linux-image-ibm-7.0Upgrade linux-image-oem-26.04Upgrade linux-image-azure-lts-26.04Upgrade linux-image-generic-64k-hwe-24.04Upgrade linux-image-oracle-7.0Upgrade linux-image-7.0.0-1013-ibmUpgrade linux-image-nvidia-64k-7.0Upgrade linux-image-7.0.0-1006-gkeUpgrade linux-image-7.0.0-2018-nvidia-bos-64kUpgrade linux-image-7.0.0-31-genericUpgrade linux-image-ibmUpgrade linux-image-7.0.0-1011-gcp-64kUpgrade linux-image-nvidia-bos-64kUpgrade linux-image-virtual-hwe-26.04Upgrade linux-image-awsUpgrade linux-image-gke-64kUpgrade linux-image-oem-7.0Upgrade linux-image-raspi-realtimeUpgrade linux-image-azureUpgrade linux-image-nvidia-bos-64k-7.0Upgrade linux-image-7.0.0-1018-nvidiaUpgrade linux-image-7.0.0-1011-oracle | Sep 14, 2026 | Sep 7, 2026 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Jul 27, 2026 | Jul 19, 2026 |
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