CVE-2026-97921

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Source
https://cve.org/CVERecord?id=CVE-2026-97921
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97921.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-97921
Downstream
Related
Published
2026-09-25T10:22:41Z
Modified
2026-10-09T17:27:00Z
Summary
tracing: Free histogram the field rejected for a bad modifier
Details

In the Linux kernel, the following vulnerability has been resolved:

tracing: Free histogram the field rejected for a bad modifier

Writing a hist trigger whose value or variable carries a modifier that is not allowed there leaks the fields that were built for it.

__create_val_field() takes the field from parse_expr() and stores it in hist_data->fields[] only after the modifier checks have run:

hist_field = parse_expr(hist_data, file, field_str, flags, var_name,
			&n_subexprs);
...
if (hist_field->flags & HIST_FIELD_FL_VAR) {
	if (hist_field->flags & (...))
		goto err;
} else {
	if (hist_field->flags & (...))
		goto err;
}

hist_data->fields[val_idx] = hist_field;

Both checks jump past that store, and the err label returns without freeing anything. The error unwinds to create_hist_data(), which calls destroy_hist_data() -> destroy_hist_fields(), and that reaches a field only by walking fields[]. A field that never got there is unreachable.

commit e0213434fe3e ("tracing: Do not let histogram values have some modifiers") set ret to -EINVAL and fell through to the store, which left the field owned by fields[] and freed along with the rest of hist_data. Splitting the check into a value case and a variable case replaced that fall-through with a goto that skips it.

With CONFIG_DEBUG_KMEMLEAK, 200 writes of

echo 'hist:keys=prev_pid:vals=next_pid.log2' > \

 events/sched/sched_switch/trigger

each correctly rejected with -EINVAL, leave 332 unreferenced objects (63744 bytes) reported at create_hist_field(); 200 install and remove cycles of a valid trigger leave none. A '.log2' field is two allocations, since create_hist_field() puts the plain field in operands[0] of the log2 field, and both are reported.

Use destroy_hist_field() rather than __destroy_hist_field() so that operands[0] is freed as well. It returns early for HIST_FIELD_FL_VAR_REF, which is what an operand owned by hist_data->var_refs[] needs; the rejected field itself is never a var ref, because a var ref never carries a modifier flag.

Database specific 
{
    "cna_assigner":  "Linux",
    "osv_generated_from":  "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97921.json"
}
References

Affected packages

Git / 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
7403630eb94c1d664fb873f967427ef2f6ee3699
Fixed
a2652fcf96b63e9da04951e4e58e6a0672df695d
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c
Fixed
3d42fed18b2c5707b6332ebe87b789fd768eb01b
Fixed
e787361bb6b0026ea3eb4d3fa7a304c7fcb99555
Fixed
b22dc0add7d72b8bd9cae3188db0dd65da1c8652
Fixed
891c21f6d5673b2a519b536243bfc6dd2d35beb6
Fixed
230234d12ce42ab04132a32c3a848f07a5d27a71
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
6.1.33
Fixed
6.1.189
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
6.3.7
Fixed
6.4
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
8d505d06d7330f5d67d3e5e9e1c647fb0b10ddad

Affected versions

v6.*
v6.1.100
v6.1.101
v6.1.102
v6.1.103
v6.1.104
v6.1.105
v6.1.106
v6.1.107
v6.1.108
v6.1.109
v6.1.110
v6.1.111
v6.1.112
v6.1.113
v6.1.114
v6.1.115
v6.1.116
v6.1.117
v6.1.118
v6.1.119
v6.1.120
v6.1.121
v6.1.122
v6.1.123
v6.1.124
v6.1.125
v6.1.126
v6.1.127
v6.1.128
v6.1.129
v6.1.130
v6.1.131
v6.1.132
v6.1.133
v6.1.134
v6.1.135
v6.1.136
v6.1.137
v6.1.138
v6.1.139
v6.1.140
v6.1.141
v6.1.142
v6.1.143
v6.1.144
v6.1.145
v6.1.146
v6.1.147
v6.1.148
v6.1.149
v6.1.150
v6.1.151
v6.1.152
v6.1.153
v6.1.154
v6.1.155
v6.1.156
v6.1.157
v6.1.158
v6.1.159
v6.1.160
v6.1.161
v6.1.162
v6.1.163
v6.1.164
v6.1.165
v6.1.166
v6.1.167
v6.1.168
v6.1.169
v6.1.170
v6.1.171
v6.1.172
v6.1.173
v6.1.174
v6.1.175
v6.1.176
v6.1.177
v6.1.178
v6.1.179
v6.1.180
v6.1.181
v6.1.182
v6.1.183
v6.1.184
v6.1.185
v6.1.186
v6.1.187
v6.1.188
v6.1.33
v6.1.34
v6.1.35
v6.1.36
v6.1.37
v6.1.38
v6.1.39
v6.1.40
v6.1.41
v6.1.42
v6.1.43
v6.1.44
v6.1.45
v6.1.46
v6.1.47
v6.1.48
v6.1.49
v6.1.50
v6.1.51
v6.1.52
v6.1.53
v6.1.54
v6.1.55
v6.1.56
v6.1.57
v6.1.58
v6.1.59
v6.1.60
v6.1.61
v6.1.62
v6.1.63
v6.1.64
v6.1.65
v6.1.66
v6.1.67
v6.1.68
v6.1.69
v6.1.70
v6.1.71
v6.1.72
v6.1.73
v6.1.74
v6.1.75
v6.1.76
v6.1.77
v6.1.78
v6.1.79
v6.1.80
v6.1.81
v6.1.82
v6.1.83
v6.1.84
v6.1.85
v6.1.86
v6.1.87
v6.1.88
v6.1.89
v6.1.90
v6.1.91
v6.1.92
v6.1.93
v6.1.94
v6.1.95
v6.1.96
v6.1.97
v6.1.98
v6.1.99
v6.3.10
v6.3.11
v6.3.12
v6.3.13
v6.3.7
v6.3.8
v6.3.9

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97921.json"

Linux / Kernel

Package

Name
Kernel

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
6.1.189
Type
ECOSYSTEM
Events
Introduced
6.2.0
Fixed
6.6.158
Type
ECOSYSTEM
Events
Introduced
6.4.0
Fixed
6.12.111
Type
ECOSYSTEM
Events
Introduced
6.7.0
Fixed
6.18.53
Type
ECOSYSTEM
Events
Introduced
6.13.0
Fixed
7.2.7

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97921.json"