{"id":"CVE-2026-97935","published":"2026-09-25T11:17:20.850","lastModified":"2026-09-25T11:17:20.850","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.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/65d1e28198f344832a8a63e8ccf84b8f65b92a32","tags":[]},{"url":"https://git.kernel.org/stable/c/6ede78d0563a2a3ae3e46f9c07cedb5d79645429","tags":[]},{"url":"https://git.kernel.org/stable/c/cfad128171f8e2237a3c723d6478ef2cfb3b9127","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}