Description
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.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
47125db27e47e9d44c878bf8925aa057824bb0d5 to < f3705db4e6378cc1b91a38ce0fe2f879055e23caaffected47125db27e47e9d44c878bf8925aa057824bb0d5 to < b589147f54adc62e4172e4acf079ad5fb7b3687faffected47125db27e47e9d44c878bf8925aa057824bb0d5 to < be0628a101ac05b085aaa4f650d48bd3915e80faaffected47125db27e47e9d44c878bf8925aa057824bb0d5 to < ca19a175e89b7de604fab736436cbab74030b47aaffected47125db27e47e9d44c878bf8925aa057824bb0d5 to < 6ac26161db27f7fb9d9e89ae240dbe52795496ccaffected47125db27e47e9d44c878bf8925aa057824bb0d5 to < 3c492c8eba02698ca893a9a13388d2adf6dfb839affected47125db27e47e9d44c878bf8925aa057824bb0d5 to < 68c4b780b266a435261a1e029bede5ee3c2735ccaffected47125db27e47e9d44c878bf8925aa057824bb0d5 to < e2b0575900ff72aa82748af96e7bd564ade5157aaffected
Linux Linux
Default version status: affected
5.9affected0 to < 5.9unaffected5.10.270 to ≤ 5.10.*unaffected5.15.221 to ≤ 5.15.*unaffected6.1.188 to ≤ 6.1.*unaffected6.6.157 to ≤ 6.6.*unaffected6.12.110 to ≤ 6.12.*unaffected6.18.51 to ≤ 6.18.*unaffected7.2.5 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/f3705db4e6378cc1b91a38ce0fe2f879055e23ca ↗
- https://git.kernel.org/stable/c/b589147f54adc62e4172e4acf079ad5fb7b3687f ↗
- https://git.kernel.org/stable/c/be0628a101ac05b085aaa4f650d48bd3915e80fa ↗
- https://git.kernel.org/stable/c/ca19a175e89b7de604fab736436cbab74030b47a ↗
- https://git.kernel.org/stable/c/6ac26161db27f7fb9d9e89ae240dbe52795496cc ↗
- https://git.kernel.org/stable/c/3c492c8eba02698ca893a9a13388d2adf6dfb839 ↗
- https://git.kernel.org/stable/c/68c4b780b266a435261a1e029bede5ee3c2735cc ↗
- https://git.kernel.org/stable/c/e2b0575900ff72aa82748af96e7bd564ade5157a ↗