CVE-2026-74633

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> tracing: Fix NULL pointer dereference in module event cache removal<br /> <br /> A module-only event filter such as ":mod:foo" is cached with a NULL<br /> event_mod-&gt;match when foo has not been loaded. If a later write tries to<br /> remove a specific match from the same module, remove_cache_mod() passes<br /> the NULL cached match to strcmp(), causing a NULL pointer dereference.<br /> <br /> The issue can be reproduced from userspace:<br /> <br /> echo &amp;#39;:mod:trace_events_kunit_missing&amp;#39; &gt; /sys/kernel/tracing/set_event<br /> echo &amp;#39;!foo_bar:mod:trace_events_kunit_missing&amp;#39; &gt;&gt; /sys/kernel/tracing/set_event<br /> <br /> The second write must be a concatenation ("&gt;&gt;") to not include O_TRUNC as<br /> that would cause ftrace_clear_events() to clear the cached modules lines.<br /> <br /> The crash was reproduced on x86_64 QEMU while KUnit workers contended on<br /> the event tracing path:<br /> <br /> BUG: kernel NULL pointer dereference, address: 0000000000000000<br /> #PF: supervisor read access in kernel mode<br /> RIP: 0010:strcmp+0x10/0x30<br /> Call Trace:<br /> __ftrace_set_clr_event_nolock+0x373/0x4a0<br /> ftrace_set_clr_event+0xf0/0x180<br /> ftrace_event_write+0xdf/0x110<br /> vfs_write+0xf6/0x440<br /> ksys_write+0x68/0xe0<br /> do_syscall_64+0xf9/0x540<br /> entry_SYSCALL_64_after_hwframe+0x77/0x7f<br /> <br /> Check event_mod-&gt;match before comparing it, consistent with the existing<br /> NULL checks for the cached system and event fields. The mismatched removal<br /> continues to return -EINVAL; a broad cached module filter is removed with<br /> "!:mod:".