CVE-2026-99141 (GCVE-0-2026-99141)
Vulnerability from cvelistv5
Published
2026-10-28 10:34
Modified
2026-10-28 10:34
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix crash in print_graph_function_event()
tracing_set_tracer() assigns the flags of the newly selected tracer
with:
tr->current_trace_flags = t->flags ? : t->tracer->flags;
If the new tracer defines neither static flags nor default flags, like
hwlat, irqsoff or wakeup, add_tracer() has no per instance flags copy
for it, and both operands are NULL, so tr->current_trace_flags ends up
being NULL as well.
The ring buffer is not cleared when switching tracers: it is reset
inside tracer_init(), after current_trace_flags was already assigned.
If the buffer still holds function_graph entries of the previous
tracer, printing one of them dereferences the NULL pointer. This was
hit by cat trace during an ftrace stress test:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
RIP: 0010:print_graph_function_event+0xe/0x20
Call Trace:
s_show+0x4d/0x110
seq_read_iter+0x2d4/0x490
seq_read+0x130/0x170
vfs_read+0xb5/0x370
ksys_read+0x6d/0xe0
do_syscall_64+0xbc/0x450
The snapshot buffer is not reset at all, so this can be reproduced
without a race:
echo function_graph > /sys/kernel/tracing/current_tracer
echo 1 > /sys/kernel/tracing/snapshot
echo hwlat > /sys/kernel/tracing/current_tracer
cat /sys/kernel/tracing/snapshot
Rather than teaching every user of tr->current_trace_flags about this
corner case, make sure it is never NULL: when the newly selected
tracer has no flags at all, tracing_set_tracer() falls back to a
static empty no_tracer_flags. run_tracer_selftest() can hit the same
case, so the same fallback is added there too. The existing users
already handle opts == NULL, so these tracers keep behaving as before.
References
Impacted products
{
"containers": {
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"versions": [
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"version": "0",
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"version": "7.2.13",
"versionType": "semver"
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"version": "7.3",
"versionType": "original_commit_for_fix"
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"cpeApplicability": [
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"vulnerable": true
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"negate": false,
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"descriptions": [
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"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix crash in print_graph_function_event()\n\ntracing_set_tracer() assigns the flags of the newly selected tracer\nwith:\n\n\ttr-\u003ecurrent_trace_flags = t-\u003eflags ? : t-\u003etracer-\u003eflags;\n\nIf the new tracer defines neither static flags nor default flags, like\nhwlat, irqsoff or wakeup, add_tracer() has no per instance flags copy\nfor it, and both operands are NULL, so tr-\u003ecurrent_trace_flags ends up\nbeing NULL as well.\n\nThe ring buffer is not cleared when switching tracers: it is reset\ninside tracer_init(), after current_trace_flags was already assigned.\nIf the buffer still holds function_graph entries of the previous\ntracer, printing one of them dereferences the NULL pointer. This was\nhit by cat trace during an ftrace stress test:\n\n BUG: kernel NULL pointer dereference, address: 0000000000000000\n #PF: supervisor read access in kernel mode\n RIP: 0010:print_graph_function_event+0xe/0x20\n Call Trace:\n s_show+0x4d/0x110\n seq_read_iter+0x2d4/0x490\n seq_read+0x130/0x170\n vfs_read+0xb5/0x370\n ksys_read+0x6d/0xe0\n do_syscall_64+0xbc/0x450\n\nThe snapshot buffer is not reset at all, so this can be reproduced\nwithout a race:\n\n echo function_graph \u003e /sys/kernel/tracing/current_tracer\n echo 1 \u003e /sys/kernel/tracing/snapshot\n echo hwlat \u003e /sys/kernel/tracing/current_tracer\n cat /sys/kernel/tracing/snapshot\n\nRather than teaching every user of tr-\u003ecurrent_trace_flags about this\ncorner case, make sure it is never NULL: when the newly selected\ntracer has no flags at all, tracing_set_tracer() falls back to a\nstatic empty no_tracer_flags. run_tracer_selftest() can hit the same\ncase, so the same fallback is added there too. The existing users\nalready handle opts == NULL, so these tracers keep behaving as before."
}
],
"providerMetadata": {
"dateUpdated": "2026-10-28T10:34:52.091Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/b1547c6ba93b8863010aa324cd20c441f886f23e"
},
{
"url": "https://git.kernel.org/stable/c/3cc117514d69067a94d6c7479730dce41e678f50"
}
],
"title": "tracing: Fix crash in print_graph_function_event()",
"x_generator": {
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}
}
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-99141",
"datePublished": "2026-10-28T10:34:52.091Z",
"dateReserved": "2026-09-25T10:25:14.395Z",
"dateUpdated": "2026-10-28T10:34:52.091Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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