CVE Catalog

CVE-2026-74633

Unknown
Published: Translated: NVD NIST

Summary

In the Linux kernel, a NULL pointer dereference occurs in the tracing module when removing events from the module cache. A module-specific event filter such as ':mod:foo' is cached with a NULL pointer when the module is not loaded. A later attempt to remove a specific match from the same module passes this NULL to strcmp(), causing a NULL pointer dereference.

Risk Assessment

The risk includes kernel panic or unauthorized memory access, potentially leading to system integrity compromise.

Recommendation

It is recommended to apply the kernel patch that adds a check for event_mod->match before comparison, and to avoid using module filters until the patch is deployed.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

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

Vulnerability data from NVD (NIST) · CISA KEV · EPSS