In the Linux kernel, the following vulnerability has been resolved: x86/kexec: Disable KCOV instrumentation after load_segments() The load_segments() function changes segment registers, invalidating GS base (which KCOV relies on for per-cpu data). When CONFIG_KCOV is enabled, any subsequent instrumented C code call (e.g. native_gdt_invalidate()) begins crashing the kernel in an endless loop. To reproduce the problem, it's sufficient to do kexec on a KCOV-instrumented kernel: $ kexec -l /boot/otherKernel $ kexec -e The real-world context for this problem is enabling crash dump collection in syzkaller. For this, the tool loads a panic kernel before fuzzing and then calls makedumpfile after the panic. This workflow requires both CONFIG_KEXEC and CONFIG_KCOV to be enabled simultaneously. Adding safeguards directly to the KCOV fast-path (__sanitizer_cov_trace_pc()) is also undesirable as it would introduce an extra performance overhead. Disabling instrumentation for the individual functions would be too fragile, so disable KCOV instrumentation for the entire machine_kexec_64.c and physaddr.c. If coverage-guided fuzzing ever needs these components in the future, other approaches should be considered. The problem is not relevant for 32 bit kernels as CONFIG_KCOV is not supported there. [ bp: Space out comment for better readability. ]
In the Linux kernel, the following vulnerability has been resolved: x86/kexec: Disable KCOV instrumentation after load_segments() The load_segments() function changes segment registers, invalidating GS base (which KCOV relies on for per-cpu data). When CONFIG_KCOV is enabled, any subsequent instrumented C code call (e.g. native_gdt_invalidate()) begins crashing the kernel in an endless loop. To reproduce the problem, it's sufficient to do kexec on a KCOV-instrumented kernel: $ kexec -l /boot/otherKernel $ kexec -e The real-world context for this problem is enabling crash dump collection in syzkaller. For this, the tool loads a panic kernel before fuzzing and then calls makedumpfile after the panic. This workflow requires both CONFIG_KEXEC and CONFIG_KCOV to be enabled simultaneously. Adding safeguards directly to the KCOV fast-path (__sanitizer_cov_trace_pc()) is also undesirable as it would introduce an extra performance overhead. Disabling instrumentation for the individual functions would be too fragile, so disable KCOV instrumentation for the entire machine_kexec_64.c and physaddr.c. If coverage-guided fuzzing ever needs these components in the future, other approaches should be considered. The problem is not relevant for 32 bit kernels as CONFIG_KCOV is not supported there. [ bp: Space out comment for better readability. ]
Update Linux/Linux to 0e96cd314c0d819c1635d68125a4d77852c2162e if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanx86/kexec: Disable KCOV instrumentation after load_segments() affects Linux/Linux (generic), Linux/Linux (generic). Severity is medium. In the Linux kernel, the following vulnerability has been resolved: x86/kexec: Disable KCOV instrumentation after load_segments() The load_segments() function changes segment registers, invalidating GS base (which KCOV relies on for per-cpu data). When CONFIG_KCOV is enabled, any subsequent instrumented C code call (e.g. native_gdt_invalidate()) begins crashing the kernel in an endless loop. To reproduce the problem, it's sufficient to do kexec on a KCOV-instrumented kernel: $ kexec -l /boot/otherKernel $ kexec -e The real-world context for this problem is enabling crash dump collection in syzkaller. For this, the tool loads a panic kernel before fuzzing and then calls makedumpfile after the panic. This workflow requires both CONFIG_KEXEC and CONFIG_KCOV to be enabled simultaneously. Adding safeguards directly to the KCOV fast-path (__sanitizer_cov_trace_pc()) is also undesirable as it would introduce an extra performance overhead. Disabling instrumentation for the individual functions would be too fragile, so disable KCOV instrumentation for the entire machine_kexec_64.c and physaddr.c. If coverage-guided fuzzing ever needs these components in the future, other approaches should be considered. The problem is not relevant for 32 bit kernels as CONFIG_KCOV is not supported there. [ bp: Space out comment for better readability. ]
AI coding agents often install or upgrade packages automatically in generic. A medium vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=0d345996e4cb573f8cc81d49b3ee9a7fd2035bef <0e96cd314c0d819c1635d68125a4d77852c2162e || >=0d345996e4cb573f8cc81d49b3ee9a7fd2035bef <593d67032544b9271094fc9b43e437e017cb2b2f || >=0d345996e4cb573f8cc81d49b3ee9a7fd2035bef <1e3e98596c2769721ade0418434852fb3af4849a || >=0d345996e4cb573f8cc81d49b3ee9a7fd2035bef <de05c66fab8847237a9ca216934e56d3ee837f08 || >=0d345996e4cb573f8cc81d49b3ee9a7fd2035bef <917e3ad3321e75ca0223d5ccf26ceda116aa51e1 | 0e96cd314c0d819c1635d68125a4d77852c2162e, 593d67032544b9271094fc9b43e437e017cb2b2f, 1e3e98596c2769721ade0418434852fb3af4849a, de05c66fab8847237a9ca216934e56d3ee837f08, 917e3ad3321e75ca0223d5ccf26ceda116aa51e1 |
| Linux/Linuxgeneric | 6.6 | Not reported |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by CVE List V5 (cvelist).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL GuardUpdate Linux/Linux to 0e96cd314c0d819c1635d68125a4d77852c2162e if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanx86/kexec: Disable KCOV instrumentation after load_segments() affects Linux/Linux (generic), Linux/Linux (generic). Severity is medium. In the Linux kernel, the following vulnerability has been resolved: x86/kexec: Disable KCOV instrumentation after load_segments() The load_segments() function changes segment registers, invalidating GS base (which KCOV relies on for per-cpu data). When CONFIG_KCOV is enabled, any subsequent instrumented C code call (e.g. native_gdt_invalidate()) begins crashing the kernel in an endless loop. To reproduce the problem, it's sufficient to do kexec on a KCOV-instrumented kernel: $ kexec -l /boot/otherKernel $ kexec -e The real-world context for this problem is enabling crash dump collection in syzkaller. For this, the tool loads a panic kernel before fuzzing and then calls makedumpfile after the panic. This workflow requires both CONFIG_KEXEC and CONFIG_KCOV to be enabled simultaneously. Adding safeguards directly to the KCOV fast-path (__sanitizer_cov_trace_pc()) is also undesirable as it would introduce an extra performance overhead. Disabling instrumentation for the individual functions would be too fragile, so disable KCOV instrumentation for the entire machine_kexec_64.c and physaddr.c. If coverage-guided fuzzing ever needs these components in the future, other approaches should be considered. The problem is not relevant for 32 bit kernels as CONFIG_KCOV is not supported there. [ bp: Space out comment for better readability. ]
AI coding agents often install or upgrade packages automatically in generic. A medium vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=0d345996e4cb573f8cc81d49b3ee9a7fd2035bef <0e96cd314c0d819c1635d68125a4d77852c2162e || >=0d345996e4cb573f8cc81d49b3ee9a7fd2035bef <593d67032544b9271094fc9b43e437e017cb2b2f || >=0d345996e4cb573f8cc81d49b3ee9a7fd2035bef <1e3e98596c2769721ade0418434852fb3af4849a || >=0d345996e4cb573f8cc81d49b3ee9a7fd2035bef <de05c66fab8847237a9ca216934e56d3ee837f08 || >=0d345996e4cb573f8cc81d49b3ee9a7fd2035bef <917e3ad3321e75ca0223d5ccf26ceda116aa51e1 | 0e96cd314c0d819c1635d68125a4d77852c2162e, 593d67032544b9271094fc9b43e437e017cb2b2f, 1e3e98596c2769721ade0418434852fb3af4849a, de05c66fab8847237a9ca216934e56d3ee837f08, 917e3ad3321e75ca0223d5ccf26ceda116aa51e1 |
| Linux/Linuxgeneric | 6.6 | Not reported |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by CVE List V5 (cvelist).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard