{"id":"CVE-2026-74633","summary":"tracing: Fix NULL pointer dereference in module event cache removal","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix NULL pointer dereference in module event cache removal\n\nA module-only event filter such as \":mod:foo\" is cached with a NULL\nevent_mod-\u003ematch when foo has not been loaded. If a later write tries to\nremove a specific match from the same module, remove_cache_mod() passes\nthe NULL cached match to strcmp(), causing a NULL pointer dereference.\n\nThe issue can be reproduced from userspace:\n\n  echo ':mod:trace_events_kunit_missing' \u003e /sys/kernel/tracing/set_event\n  echo '!foo_bar:mod:trace_events_kunit_missing' \u003e\u003e /sys/kernel/tracing/set_event\n\nThe second write must be a concatenation (\"\u003e\u003e\") to not include O_TRUNC as\nthat would cause ftrace_clear_events() to clear the cached modules lines.\n\nThe crash was reproduced on x86_64 QEMU while KUnit workers contended on\nthe event tracing path:\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000000\n  #PF: supervisor read access in kernel mode\n  RIP: 0010:strcmp+0x10/0x30\n  Call Trace:\n   __ftrace_set_clr_event_nolock+0x373/0x4a0\n   ftrace_set_clr_event+0xf0/0x180\n   ftrace_event_write+0xdf/0x110\n   vfs_write+0xf6/0x440\n   ksys_write+0x68/0xe0\n   do_syscall_64+0xf9/0x540\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nCheck event_mod-\u003ematch before comparing it, consistent with the existing\nNULL checks for the cached system and event fields. The mismatched removal\ncontinues to return -EINVAL; a broad cached module filter is removed with\n\"!:mod:\u003cmodule\u003e\".","modified":"2026-08-24T11:47:10.569010029Z","published":"2026-08-22T15:32:13.808Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74633.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/152a00440dc6ef62c6e4cf9bd881a7e6bb81fda9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ad4e9dd5fec7a322a471ff36fb9c76214e3c6992"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b69859204d4db3acd86c1c2dadcef0d77b451933"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74633.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74633"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"b355247df104ef6644288884afd2c08b7bf49897"},{"fixed":"152a00440dc6ef62c6e4cf9bd881a7e6bb81fda9"},{"fixed":"ad4e9dd5fec7a322a471ff36fb9c76214e3c6992"},{"fixed":"b69859204d4db3acd86c1c2dadcef0d77b451933"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74633.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.14.0"},{"fixed":"6.18.45"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74633.json"}}],"schema_version":"1.9.0"}