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CVE-2026-89984

perf/x86/intel: Fix kernel address leakages in LBR stack

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, and 2 more
None on Exploit-DB, Metasploit or GitHub

Summary

In the Linux kernel, the following vulnerability has been resolved: perf/x86/intel: Fix kernel address leakages in LBR stack Before Arch LBR gained CPL filtering support, a user-only branch stack could still contain kernel addresses. As a result, kernel branch records may be exposed to user space even when PERF_SAMPLE_BRANCH_USER is requested. For example, on Intel Tiger Lake, the following command can still report SYSRET/ERET entries with kernel-space from addresses: $ ./perf record -e cycles:p -o - --branch-filter any,save_type,u -- \ ./perf bench syscall basic --loop 1000 | \ ./perf script -i - --fields brstack|tr ' ' '\n'| \ grep -E '0x[89a-f][0-9a-f]{15}' Total time: 0.000 [sec] 0.219000 usecs/op 4,566,210 ops/sec [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.551 MB - ] 0xffffffff93c001c8/0x7f12a2b1d647/P/-/-/16959/SYSRET/- 0xffffffff93c001c8/0x7f12a2b1d5c2/P/-/-/17535/SYSRET/- 0xffffffff93c01928/0x7f12a2861000/P/-/-/6719/ERET/- 0xffffffff93c01928/0x7f12a297a000/P/-/-/8575/ERET/- The problem is that intel_pmu_lbr_filter() does not fully validate the privilege level of sampled entries. It filters some mismatches based on the branch type and the to address, but it does not reject entries whose from address violates the requested branch privilege filter. Fix this by extending software filtering to validate both from and to addresses against br_sel. Any LBR entry contains kernel address does not match the requested user filter is dropped. This prevents kernel addresses from appearing in user-only branch stacks.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From 47125db27e47e9d44c878bf8925aa057824bb0d5 · fixed in f3705db4e6378cc1b91a38ce0fe2f879055e23ca; From 47125db27e47e9d44c878bf8925aa057824bb0d5 · fixed in b589147f54adc62e4172e4acf079ad5fb7b3687f; From 47125db27e47e9d44c878bf8925aa057824bb0d5 · fixed in be0628a101ac05b085aaa4f650d48bd3915e80fa; From 47125db27e47e9d44c878bf8925aa057824bb0d5 · fixed in ca19a175e89b7de604fab736436cbab74030b47a; From 47125db27e47e9d44c878bf8925aa057824bb0d5 · fixed in 6ac26161db27f7fb9d9e89ae240dbe52795496cc; From 47125db27e47e9d44c878bf8925aa057824bb0d5 · fixed in 3c492c8eba02698ca893a9a13388d2adf6dfb839; From 47125db27e47e9d44c878bf8925aa057824bb0d5 · fixed in 68c4b780b266a435261a1e029bede5ee3c2735cc; From 47125db27e47e9d44c878bf8925aa057824bb0d5 · fixed in e2b0575900ff72aa82748af96e7bd564ade5157a

  • Linux Linux

    5.9

  • KernelLinux

    From 5.9.0 · fixed in 5.10.270; From 5.11.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.110; From 6.13.0 · fixed in 6.18.51; From 6.19.0 · fixed in 7.2.5

References 8

git.kernel.org