{"id":"CVE-2026-98132","state":"PUBLISHED","title":"bpf: don't downgrade half-dead scalar zero spills to STACK_ZERO","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: don't downgrade half-dead scalar zero spills to STACK_ZERO\n\nstates.c:__clean_func_state() can downgrade scalar zero spill to\nSTACK_ZERO in the following case:\n\n  *(u64 *)(r10 - 8) = 0;\n  ... checkpoint ...\n  r1 = *(u32 *)(r10 - 4);\n  ... no reads from r10-8 ...\n\nHere 4 bytes at r10-8 are dead and verifier changes scalar spill to a\ncombination: 0000pppp (p stands for poison). Such a change breaks\nprecision propagation chains. All places that produce STACK_ZERO\nshould call bpf_mark_chain_precision() for the zero source.\n\nThis patch fixes the bug in a simplest way possible:\navoids converting stack spills of zero to STACK_ZERO.\nTwo smarter approaches are possible:\n- do bpf_mark_chain_precision() from __clean_func_state()\n- check slot liveness information in check_stack_write_fixed_off()\n\nI investigated both and the changes required are a bit tricky,\nhence go with a simple fix for the time being.","publishedAt":"2026-09-25T10:36:11.662Z","updatedAt":"2026-10-19T09:14:26.212Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"be23266b4a08540aa43d8503a2ea10247c8daebe","status":"affected","lessThan":"436fa689630b741a77ef8c4a6f426479affd5bac","versionType":"git"},{"version":"be23266b4a08540aa43d8503a2ea10247c8daebe","status":"affected","lessThan":"2f3536bff8823d3c5fdbbe15e17bfca696cc2b2e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/states.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.1","versionType":"semver"},{"version":"7.2.7","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/states.c"]}],"references":["https://git.kernel.org/stable/c/436fa689630b741a77ef8c4a6f426479affd5bac","https://git.kernel.org/stable/c/2f3536bff8823d3c5fdbbe15e17bfca696cc2b2e"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98132.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98132","state":"PUBLISHED","datePublished":"2026-09-25T10:36:11.662Z","dateUpdated":"2026-10-19T09:14:26.212Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.318Z"},"containers":{"cna":{"title":"bpf: don't downgrade half-dead scalar zero spills to STACK_ZERO","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: don't downgrade half-dead scalar zero spills to STACK_ZERO\n\nstates.c:__clean_func_state() can downgrade scalar zero spill to\nSTACK_ZERO in the following case:\n\n  *(u64 *)(r10 - 8) = 0;\n  ... checkpoint ...\n  r1 = *(u32 *)(r10 - 4);\n  ... no reads from r10-8 ...\n\nHere 4 bytes at r10-8 are dead and verifier changes scalar spill to a\ncombination: 0000pppp (p stands for poison). Such a change breaks\nprecision propagation chains. All places that produce STACK_ZERO\nshould call bpf_mark_chain_precision() for the zero source.\n\nThis patch fixes the bug in a simplest way possible:\navoids converting stack spills of zero to STACK_ZERO.\nTwo smarter approaches are possible:\n- do bpf_mark_chain_precision() from __clean_func_state()\n- check slot liveness information in check_stack_write_fixed_off()\n\nI investigated both and the changes required are a bit tricky,\nhence go with a simple fix for the time being."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"be23266b4a08540aa43d8503a2ea10247c8daebe","status":"affected","lessThan":"436fa689630b741a77ef8c4a6f426479affd5bac","versionType":"git"},{"version":"be23266b4a08540aa43d8503a2ea10247c8daebe","status":"affected","lessThan":"2f3536bff8823d3c5fdbbe15e17bfca696cc2b2e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/states.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.1","versionType":"semver"},{"version":"7.2.7","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/states.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/436fa689630b741a77ef8c4a6f426479affd5bac"},{"url":"https://git.kernel.org/stable/c/2f3536bff8823d3c5fdbbe15e17bfca696cc2b2e"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:14:26.212Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.2.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}