{"id":"CVE-2026-98584","state":"PUBLISHED","title":"net/sched: fix potential stack infoleak in em_text_dump()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fix potential stack infoleak in em_text_dump()\n\nem_text_dump() allocates struct tcf_em_text on the stack without zeroing\nit.  strscpy() writes the algorithm name and a NUL terminator into\nconf.algo[], leaving the remaining bytes uninitialised.  nla_put_nohdr()\nthen copies the full struct to the netlink response.\n\nKMSAN on Linux 7.2-rc6 reports two kernel-infoleak splats from this path,\none triggered via \"tc filter show\" and one via a raw RTM_GETTFILTER dump:\n\n  BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x1c9/0x2620\n    nla_put_nohdr+0x83/0x130\n    em_text_dump+0x291/0x550\n  Local variable conf created at: em_text_dump+0x5d/0x550\n  Bytes 168-179 of 199 are uninitialized\n\nI am not certain whether this constitutes a real security problem in\npractice: the test was conducted in a controlled KMSAN environment and\nthe leaked stack bytes may or may not carry sensitive data on actual\nproduction kernels.  I am reporting it because KMSAN flagged it as a\nkernel-infoleak and the fix is straightforward.  I can provide a\nuserspace reproducer on request.\n\nThe original code used strncpy() which zero-pads to the destination size.\nCommit b04202d6065c (\"net/sched: replace strncpy with strscpy\") replaced\nit with strscpy(), which does not pad, creating this condition.\nZero-initialising the struct closes it.","publishedAt":"2026-10-18T15:18:57.204Z","updatedAt":"2026-10-19T09:22:09.980Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b04202d6065cba5dfd51fb9866400b25573eac67","status":"affected","lessThan":"9923e1c537f91f3530b52d4efce85f3d9c131bf8","versionType":"git"},{"version":"b04202d6065cba5dfd51fb9866400b25573eac67","status":"affected","lessThan":"0b160417826d22f24fc31a5b9cfae3b14aa70f76","versionType":"git"},{"version":"b04202d6065cba5dfd51fb9866400b25573eac67","status":"affected","lessThan":"9c572a83037a7dcd653ba3a9cc468c16b857d0c9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/em_text.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.18.55","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.9","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":["net/sched/em_text.c"]}],"references":["https://git.kernel.org/stable/c/9923e1c537f91f3530b52d4efce85f3d9c131bf8","https://git.kernel.org/stable/c/0b160417826d22f24fc31a5b9cfae3b14aa70f76","https://git.kernel.org/stable/c/9c572a83037a7dcd653ba3a9cc468c16b857d0c9"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98584.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98584","state":"PUBLISHED","datePublished":"2026-10-18T15:18:57.204Z","dateUpdated":"2026-10-19T09:22:09.980Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.358Z"},"containers":{"cna":{"title":"net/sched: fix potential stack infoleak in em_text_dump()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fix potential stack infoleak in em_text_dump()\n\nem_text_dump() allocates struct tcf_em_text on the stack without zeroing\nit.  strscpy() writes the algorithm name and a NUL terminator into\nconf.algo[], leaving the remaining bytes uninitialised.  nla_put_nohdr()\nthen copies the full struct to the netlink response.\n\nKMSAN on Linux 7.2-rc6 reports two kernel-infoleak splats from this path,\none triggered via \"tc filter show\" and one via a raw RTM_GETTFILTER dump:\n\n  BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x1c9/0x2620\n    nla_put_nohdr+0x83/0x130\n    em_text_dump+0x291/0x550\n  Local variable conf created at: em_text_dump+0x5d/0x550\n  Bytes 168-179 of 199 are uninitialized\n\nI am not certain whether this constitutes a real security problem in\npractice: the test was conducted in a controlled KMSAN environment and\nthe leaked stack bytes may or may not carry sensitive data on actual\nproduction kernels.  I am reporting it because KMSAN flagged it as a\nkernel-infoleak and the fix is straightforward.  I can provide a\nuserspace reproducer on request.\n\nThe original code used strncpy() which zero-pads to the destination size.\nCommit b04202d6065c (\"net/sched: replace strncpy with strscpy\") replaced\nit with strscpy(), which does not pad, creating this condition.\nZero-initialising the struct closes it."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b04202d6065cba5dfd51fb9866400b25573eac67","status":"affected","lessThan":"9923e1c537f91f3530b52d4efce85f3d9c131bf8","versionType":"git"},{"version":"b04202d6065cba5dfd51fb9866400b25573eac67","status":"affected","lessThan":"0b160417826d22f24fc31a5b9cfae3b14aa70f76","versionType":"git"},{"version":"b04202d6065cba5dfd51fb9866400b25573eac67","status":"affected","lessThan":"9c572a83037a7dcd653ba3a9cc468c16b857d0c9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/em_text.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.18.55","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.9","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":["net/sched/em_text.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/9923e1c537f91f3530b52d4efce85f3d9c131bf8"},{"url":"https://git.kernel.org/stable/c/0b160417826d22f24fc31a5b9cfae3b14aa70f76"},{"url":"https://git.kernel.org/stable/c/9c572a83037a7dcd653ba3a9cc468c16b857d0c9"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:22:09.980Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"6.18.55"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"7.2.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}