CVE-2026-80602

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

State: Published
Severity: Not scored
Published: Aug 28, 2026
Updated: Oct 30, 2026
Reserved: Aug 26, 2026

Description

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.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	f4f925dae7419fc7a10af539c073871927ce3a24 to before 5adfec05e804ce4bd3368b75df5e5b7b40ee960bAffected f4f925dae7419fc7a10af539c073871927ce3a24 to before 5be478c1e08981ca91b34de310d7e2638171d9d8Affected f4f925dae7419fc7a10af539c073871927ce3a24 to before 208ecca408b1707ad86ea247d3d3e09d3606fc13Affected f4f925dae7419fc7a10af539c073871927ce3a24 to before 5ab0eba9c8819506bcb72348fd701f8a9006f95eAffected f4f925dae7419fc7a10af539c073871927ce3a24 to before fb3b76b5ad2ebad63dd76f8b65b624eaf638b73fAffected f4f925dae7419fc7a10af539c073871927ce3a24 to before 2a892294b83f541115c94b0bb637f39bef187657Affected
LinuxLinux	6.1Affected before 6.1Not affected 6.1.191 through 6.1.Not affected 6.6.145 through 6.6.Not affected 6.12.97 through 6.12.Not affected 6.18.40 through 6.18.Not affected 7.1.5 through 7.1.*Not affected 7.2 and laterNot affected

Product

Versions

LinuxLinux

f4f925dae7419fc7a10af539c073871927ce3a24 to before 5adfec05e804ce4bd3368b75df5e5b7b40ee960bAffected
f4f925dae7419fc7a10af539c073871927ce3a24 to before 5be478c1e08981ca91b34de310d7e2638171d9d8Affected
f4f925dae7419fc7a10af539c073871927ce3a24 to before 208ecca408b1707ad86ea247d3d3e09d3606fc13Affected
f4f925dae7419fc7a10af539c073871927ce3a24 to before 5ab0eba9c8819506bcb72348fd701f8a9006f95eAffected
f4f925dae7419fc7a10af539c073871927ce3a24 to before fb3b76b5ad2ebad63dd76f8b65b624eaf638b73fAffected
f4f925dae7419fc7a10af539c073871927ce3a24 to before 2a892294b83f541115c94b0bb637f39bef187657Affected

LinuxLinux

6.1Affected
before 6.1Not affected
6.1.191 through 6.1.*Not affected
6.6.145 through 6.6.*Not affected
6.12.97 through 6.12.*Not affected
6.18.40 through 6.18.*Not affected
7.1.5 through 7.1.*Not affected
7.2 and laterNot affected

References

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