In the Linux kernel, the following vulnerability has been resolved:
net_sched: gen_estimator: fix est_timer() vs CONFIG_PREEMPT_RT=y
syzbot reported a WARNING in est_timer() [1]
Problem here is that with CONFIG_PREEMPT_RT=y, timer callbacks can be preempted.
Adopt preempt_disable_nested()/preempt_enable_nested() to fix this.
[1] WARNING: CPU: 0 PID: 16 at ./include/linux/seqlock.h:221 __seqprop_assert include/linux/seqlock.h:221 [inline] WARNING: CPU: 0 PID: 16 at ./include/linux/seqlock.h:221 est_timer+0x6dc/0x9f0 net/core/gen_estimator.c:93 Modules linked in: CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:__seqprop_assert include/linux/seqlock.h:221 [inline] RIP: 0010:est_timer+0x6dc/0x9f0 net/core/gen_estimator.c:93 Call Trace: <TASK> call_timer_fn+0x17e/0x5f0 kernel/time/timer.c:1747 expire_timers kernel/time/timer.c:1798 [inline] __run_timers kernel/time/timer.c:2372 [inline] __run_timer_base+0x648/0x970 kernel/time/timer.c:2384 run_timer_base kernel/time/timer.c:2393 [inline] run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2403 handle_softirqs+0x22c/0x710 kernel/softirq.c:579 __do_softirq kernel/softirq.c:613 [inline] run_ktimerd+0xcf/0x190 kernel/softirq.c:1043 smpboot_thread_fn+0x53f/0xa60 kernel/smpboot.c:160 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>
CVSS Details
- CVSS 3.1 Base Score: 5.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade kernel6.12-tools-develUpgrade kernel6.12-headersUpgrade kernel6.12-develUpgrade perf6.12Upgrade kernel6.12Upgrade kernel6.12-libbpf-debuginfoUpgrade kernel6.12-modules-extra-commonUpgrade python3-perf6.12Upgrade kernel6.12-debuginfo-common-x86_64Upgrade kernel6.12-modules-extraUpgrade kernel6.12-toolsUpgrade kernel6.12-debuginfo-common-aarch64Upgrade bpftool6.12Upgrade kernel6.12-libbpf-develUpgrade python3-perf6.12-debuginfoUpgrade kernel6.12-tools-debuginfoUpgrade kernel6.12-debuginfoUpgrade kernel6.12-libbpf-staticUpgrade bpftool6.12-debuginfoUpgrade kernel6.12-libbpfUpgrade perf6.12-debuginfoUpgrade kernel-livepatch-6.12.46-66.121 | Oct 16, 2025 | Oct 1, 2025 |
| Debian | — | Upgrade linux | Jul 23, 2026 | Jul 23, 2026 |
| Oracle_linux | — | Upgrade kernel-uek | Nov 11, 2025 | Oct 1, 2025 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Oct 1, 2025 |
| Suse | — | Upgrade kernel-default-baseUpgrade kernel-64kb-extraUpgrade dtb-mediatekUpgrade kernel-symsUpgrade dlm-kmp-rtUpgrade kernel-macrosUpgrade kselftests-kmp-rtUpgrade dtb-xilinxUpgrade cluster-md-kmp-defaultUpgrade kselftests-kmp-defaultUpgrade kernel-obs-qaUpgrade dtb-apmUpgrade dtb-nvidiaUpgrade kernel-develUpgrade kernel-64kb-develUpgrade dtb-rockchipUpgrade dtb-qcomUpgrade kernel-rt-livepatchUpgrade kernel-default-optionalUpgrade kernel-default-livepatch-develUpgrade cluster-md-kmp-64kbUpgrade dtb-sprdUpgrade kernel-defaultUpgrade kernel-rtUpgrade dlm-kmp-defaultUpgrade cluster-md-kmp-rtUpgrade kernel-rt-livepatch-develUpgrade kernel-rt-develUpgrade dtb-armUpgrade kernel-rt-optionalUpgrade kernel-source-vanillaUpgrade kernel-docs-htmlUpgrade kernel-default-develUpgrade kernel-kvmsmall-develUpgrade dtb-exynosUpgrade kernel-64kbUpgrade kernel-kvmsmall-vdsoUpgrade kernel-rt-extraUpgrade dtb-marvellUpgrade dtb-appleUpgrade dlm-kmp-64kbUpgrade dtb-amazonUpgrade dtb-freescaleUpgrade dtb-caviumUpgrade kernel-zfcpdumpUpgrade dtb-hisiliconUpgrade gfs2-kmp-rtUpgrade kernel-rt-vdsoUpgrade kernel-default-vdsoUpgrade kernel-default-livepatchUpgrade kselftests-kmp-64kbUpgrade kernel-kvmsmallUpgrade kernel-64kb-optionalUpgrade dtb-renesasUpgrade dtb-allwinnerUpgrade ocfs2-kmp-defaultUpgrade ocfs2-kmp-64kbUpgrade gfs2-kmp-64kbUpgrade reiserfs-kmp-defaultUpgrade dtb-broadcomUpgrade kernel-obs-buildUpgrade dtb-lgUpgrade dtb-alteraUpgrade kernel-sourceUpgrade dtb-socionextUpgrade gfs2-kmp-defaultUpgrade dtb-amdUpgrade ocfs2-kmp-rtUpgrade kernel-default-extraUpgrade kernel-docsUpgrade dtb-amlogic | Dec 5, 2025 | Nov 6, 2025 |
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