{"id":"CVE-2026-97935","state":"PUBLISHED","title":"tracing: Set the trace clock before registering the histogram trigger","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Set the trace clock before registering the histogram trigger\n\nhist_register_trigger() puts the trigger on the global named_triggers\nlist in cmd_ops->init(), and only then sets the trace clock:\n\n\tif (data->cmd_ops->init) {\n\t\tret = data->cmd_ops->init(data);\n\t\tif (ret < 0)\n\t\t\tgoto out;\n\t}\n\n\tif (hist_data->enable_timestamps) {\n\t\tret = tracing_set_clock(file->tr, hist_data->attrs->clock);\n\t\tif (ret) {\n\t\t\thist_err(tr, HIST_ERR_SET_CLOCK_FAIL, errpos(clock));\n\t\t\tgoto out;\n\t\t}\n\nThe clock string is not checked anywhere before that call, so a named\ntrigger using common_timestamp with an unknown clock fails after it has\nalready become findable. event_hist_trigger_parse() then frees it\nwithout taking it off the list, and the next lookup by name reads the\nfreed object:\n\n ~# cd /sys/kernel/tracing/events/sched/sched_switch\n ~# echo 'hist:name=foo:keys=common_pid:ts=common_timestamp:clock=bogus' > trigger\n bash: echo: write error: Invalid argument\n ~# echo 'hist:name=foo:keys=common_pid' > trigger\n\n  BUG: KASAN: slab-use-after-free in find_named_trigger+0xac/0xc0\n  Read of size 8 at addr ffff88800915d760 by task init/1\n   find_named_trigger+0xac/0xc0\n   hist_register_trigger+0xc1/0x900\n   event_hist_trigger_parse+0x3146/0x6af0\n   event_trigger_write+0xce/0x160\n  Freed by task 63:\n   kfree+0x154/0x420\n   trigger_kthread_fn+0xfd/0x160\n\nSet the clock before the trigger is registered, so that nothing which\ncan fail runs after it is published, the way commit 6f86bdeab633\n(\"tracing: Fix bad hist from corrupting named_triggers list\") moved the\nregistration below the rest of the setup.\n\ntracing_set_filter_buffering() is reference counted, so the init failure\npath has to drop the reference that the clock block now takes first.","publishedAt":"2026-09-25T10:22:49.820Z","updatedAt":"2026-10-30T12:37:45.761Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"85e6df6e9cd489de8e238596a68b89eee0c03b88","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"3568dabef3fb56517777ab981584f72ab1e90186","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"c7b77c22adcf314ec8aa4807f01914dcbc62ed54","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"578d39ab420b18b76a12fc8d0573ec041a84da28","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"cc6c4cf565b0c187c61ffd2e67a4dfb2427675ad","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"cfad128171f8e2237a3c723d6478ef2cfb3b9127","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"65d1e28198f344832a8a63e8ccf84b8f65b92a32","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"6ede78d0563a2a3ae3e46f9c07cedb5d79645429","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/trace_events_hist.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.17","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.53","status":"unaffected","lessThanOrEqual":"6.18.*","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/trace/trace_events_hist.c"]}],"references":["https://git.kernel.org/stable/c/85e6df6e9cd489de8e238596a68b89eee0c03b88","https://git.kernel.org/stable/c/3568dabef3fb56517777ab981584f72ab1e90186","https://git.kernel.org/stable/c/c7b77c22adcf314ec8aa4807f01914dcbc62ed54","https://git.kernel.org/stable/c/578d39ab420b18b76a12fc8d0573ec041a84da28","https://git.kernel.org/stable/c/cc6c4cf565b0c187c61ffd2e67a4dfb2427675ad","https://git.kernel.org/stable/c/cfad128171f8e2237a3c723d6478ef2cfb3b9127","https://git.kernel.org/stable/c/65d1e28198f344832a8a63e8ccf84b8f65b92a32","https://git.kernel.org/stable/c/6ede78d0563a2a3ae3e46f9c07cedb5d79645429"],"weaknesses":[],"ingestedAt":"2026-10-30T12:56:04.490Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/97xxx/CVE-2026-97935.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-97935","state":"PUBLISHED","datePublished":"2026-09-25T10:22:49.820Z","dateUpdated":"2026-10-30T12:37:45.761Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:18:58.203Z"},"containers":{"cna":{"title":"tracing: Set the trace clock before registering the histogram trigger","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Set the trace clock before registering the histogram trigger\n\nhist_register_trigger() puts the trigger on the global named_triggers\nlist in cmd_ops->init(), and only then sets the trace clock:\n\n\tif (data->cmd_ops->init) {\n\t\tret = data->cmd_ops->init(data);\n\t\tif (ret < 0)\n\t\t\tgoto out;\n\t}\n\n\tif (hist_data->enable_timestamps) {\n\t\tret = tracing_set_clock(file->tr, hist_data->attrs->clock);\n\t\tif (ret) {\n\t\t\thist_err(tr, HIST_ERR_SET_CLOCK_FAIL, errpos(clock));\n\t\t\tgoto out;\n\t\t}\n\nThe clock string is not checked anywhere before that call, so a named\ntrigger using common_timestamp with an unknown clock fails after it has\nalready become findable. event_hist_trigger_parse() then frees it\nwithout taking it off the list, and the next lookup by name reads the\nfreed object:\n\n ~# cd /sys/kernel/tracing/events/sched/sched_switch\n ~# echo 'hist:name=foo:keys=common_pid:ts=common_timestamp:clock=bogus' > trigger\n bash: echo: write error: Invalid argument\n ~# echo 'hist:name=foo:keys=common_pid' > trigger\n\n  BUG: KASAN: slab-use-after-free in find_named_trigger+0xac/0xc0\n  Read of size 8 at addr ffff88800915d760 by task init/1\n   find_named_trigger+0xac/0xc0\n   hist_register_trigger+0xc1/0x900\n   event_hist_trigger_parse+0x3146/0x6af0\n   event_trigger_write+0xce/0x160\n  Freed by task 63:\n   kfree+0x154/0x420\n   trigger_kthread_fn+0xfd/0x160\n\nSet the clock before the trigger is registered, so that nothing which\ncan fail runs after it is published, the way commit 6f86bdeab633\n(\"tracing: Fix bad hist from corrupting named_triggers list\") moved the\nregistration below the rest of the setup.\n\ntracing_set_filter_buffering() is reference counted, so the init failure\npath has to drop the reference that the clock block now takes first."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"85e6df6e9cd489de8e238596a68b89eee0c03b88","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"3568dabef3fb56517777ab981584f72ab1e90186","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"c7b77c22adcf314ec8aa4807f01914dcbc62ed54","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"578d39ab420b18b76a12fc8d0573ec041a84da28","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"cc6c4cf565b0c187c61ffd2e67a4dfb2427675ad","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"cfad128171f8e2237a3c723d6478ef2cfb3b9127","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"65d1e28198f344832a8a63e8ccf84b8f65b92a32","versionType":"git"},{"version":"a4072fe85ba3671720cab0788291af953db27318","status":"affected","lessThan":"6ede78d0563a2a3ae3e46f9c07cedb5d79645429","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/trace_events_hist.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.17","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.53","status":"unaffected","lessThanOrEqual":"6.18.*","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/trace/trace_events_hist.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/85e6df6e9cd489de8e238596a68b89eee0c03b88"},{"url":"https://git.kernel.org/stable/c/3568dabef3fb56517777ab981584f72ab1e90186"},{"url":"https://git.kernel.org/stable/c/c7b77c22adcf314ec8aa4807f01914dcbc62ed54"},{"url":"https://git.kernel.org/stable/c/578d39ab420b18b76a12fc8d0573ec041a84da28"},{"url":"https://git.kernel.org/stable/c/cc6c4cf565b0c187c61ffd2e67a4dfb2427675ad"},{"url":"https://git.kernel.org/stable/c/cfad128171f8e2237a3c723d6478ef2cfb3b9127"},{"url":"https://git.kernel.org/stable/c/65d1e28198f344832a8a63e8ccf84b8f65b92a32"},{"url":"https://git.kernel.org/stable/c/6ede78d0563a2a3ae3e46f9c07cedb5d79645429"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:37:45.761Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"5.10.273"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"5.15.224"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"6.12.112"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"6.18.53"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"7.2.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}