KVM: s390: Free guest debug data on vcpu destroy

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89923
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-16 11:17:01 UTC
Updated2026-09-16 11:17:01 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: KVM: s390: Free guest debug data on vcpu destroy kvm_s390_clear_bp_data() is only called from kvm_arch_vcpu_ioctl_set_guest_debug(), i.e. when user space changes or disables debugging. A vCPU that is destroyed while hardware breakpoints are still armed - the normal case when the VMM just exits or crashes - leaks hw_bp_info, hw_wp_info and all old_data buffers, since generic KVM frees the vCPU right after kvm_arch_vcpu_destroy(). That is bounded by MAX_BP_COUNT entries, so roughly 8 KiB per vCPU, but it is unbounded over VM lifetimes. The allocations are GFP_KERNEL_ACCOUNT, so the charge also outlives the exiting process and pins dying memcgs. Fix by clearing the debug data on vCPU destruction. Calling it unconditionally is fine: struct kvm_vcpu is zero allocated, so for a vCPU that never enabled debugging the counters are 0 and the pointers NULL.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 27291e2165b6de70c476b7b675308113edd69a60 053f2068cf9b0654b651fed5ad7649d3deb982bf git Not specified
CNA Linux Linux affected 27291e2165b6de70c476b7b675308113edd69a60 6c996b12bbe4a6023076e8eee3cfaf2cc99db76c git Not specified
CNA Linux Linux affected 27291e2165b6de70c476b7b675308113edd69a60 d6280fc540d8f4653c9b54a78cb747e128070f5e git Not specified
CNA Linux Linux affected 27291e2165b6de70c476b7b675308113edd69a60 544a5a665019cef394ce8bda97fa7a2cab253781 git Not specified
CNA Linux Linux affected 27291e2165b6de70c476b7b675308113edd69a60 9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63 git Not specified
CNA Linux Linux affected 27291e2165b6de70c476b7b675308113edd69a60 b5acacfdb8966abff91836c1c5bd7da59d8a526e git Not specified
CNA Linux Linux affected 27291e2165b6de70c476b7b675308113edd69a60 e4d8b7f176b976474e0800ba71ee2dfa3ce263c9 git Not specified
CNA Linux Linux affected 27291e2165b6de70c476b7b675308113edd69a60 e7f698b09d4a7c36b299acf680fc50fe868e2bcd git Not specified
CNA Linux Linux affected 3.16 Not specified
CNA Linux Linux unaffected 3.16 semver Not specified
CNA Linux Linux unaffected 5.10.270 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.221 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.188 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.157 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.110 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.51 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.5 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/e7f698b09d4a7c36b299acf680fc50fe868e2bcd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6c996b12bbe4a6023076e8eee3cfaf2cc99db76c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/544a5a665019cef394ce8bda97fa7a2cab253781 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e4d8b7f176b976474e0800ba71ee2dfa3ce263c9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/053f2068cf9b0654b651fed5ad7649d3deb982bf 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b5acacfdb8966abff91836c1c5bd7da59d8a526e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d6280fc540d8f4653c9b54a78cb747e128070f5e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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