CVE-2026-80602 PUBLISHED

perf/x86/amd/lbr: Fix kernel address leakage

Assigner: Linux
Reserved: 26.08.2026 Published: 28.08.2026 Updated: 28.08.2026

In the Linux kernel, the following vulnerability has been resolved:

perf/x86/amd/lbr: Fix kernel address leakage

A user-only branch stack can contain branches that originate from the kernel. As a result, kernel addresses are exposed to user space even when PERF_SAMPLE_BRANCH_USER is requested. On AMD processors supporting X86_FEATURE_AMD_LBR_V2, perf can still report SYSRET/ERET entries for which the branch-from addresses are in the kernel.

E.g.

$ perf record -e cycles -o - -j any,save_type,u -- \ perf bench syscall basic --loop 1000 | \ perf script -i - -F brstack|tr ' ' '\n'| \ grep -E '0x[89a-f][0-9a-f]{15}'

... 0xffffffff81001268/0x717a90a38f1a/M/-/-/0/ERET/NON_SPEC_CORRECT_PATH 0xffffffff81001268/0x717a90a39157/M/-/-/0/ERET/NON_SPEC_CORRECT_PATH 0xffffffff81001268/0x717a90a2c628/M/-/-/0/ERET/NON_SPEC_CORRECT_PATH 0xffffffff81001268/0x717a90a41b60/M/-/-/0/ERET/NON_SPEC_CORRECT_PATH 0xffffffff81001268/0x717a90a260db/M/-/-/0/ERET/NON_SPEC_CORRECT_PATH 0xffffffff81001268/0x717a90a260db/M/-/-/0/ERET/NON_SPEC_CORRECT_PATH 0xffffffff81001268/0x717a8bef1c30/M/-/-/0/ERET/NON_SPEC_CORRECT_PATH 0xffffffff81001268/0x717a8e4d3c90/M/-/-/0/ERET/NON_SPEC_CORRECT_PATH ...

The reason is that the hardware filter only considers the privilege level applicable to the branch target. Extend software filtering to also validate the branch-from addresses against br_sel, so that any branch record whose branch-from address is in the kernel is dropped when PERF_SAMPLE_BRANCH_USER is requested.

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from f4f925dae7419fc7a10af539c073871927ce3a24 to 5be478c1e08981ca91b34de310d7e2638171d9d8 (excl.)
  • affected from f4f925dae7419fc7a10af539c073871927ce3a24 to 208ecca408b1707ad86ea247d3d3e09d3606fc13 (excl.)
  • affected from f4f925dae7419fc7a10af539c073871927ce3a24 to 5ab0eba9c8819506bcb72348fd701f8a9006f95e (excl.)
  • affected from f4f925dae7419fc7a10af539c073871927ce3a24 to fb3b76b5ad2ebad63dd76f8b65b624eaf638b73f (excl.)
  • affected from f4f925dae7419fc7a10af539c073871927ce3a24 to 2a892294b83f541115c94b0bb637f39bef187657 (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 6.1 is affected
  • unaffected from 0 to 6.1 (excl.)
  • unaffected from 6.6.145 to 6.6.* (incl.)
  • unaffected from 6.12.97 to 6.12.* (incl.)
  • unaffected from 6.18.40 to 6.18.* (incl.)
  • unaffected from 7.1.5 to 7.1.* (incl.)
  • unaffected from 7.2 to * (incl.)

References