CVE-2026-97921— tracing: Free histogram the field rejected for a bad modifier
Quick assessment
Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
以下是该漏洞描述信息的中文翻译： 在 Linux 内核中，已修复以下漏洞： 跟踪（tracing）：释放因修饰符错误而被拒绝的直方图字段 当编写一个 hist 触发器，其值或变量携带了不允许的修饰符时，会导致为其构建的字段发生内存泄漏。 函数从 获取字段，但该字段只有在修饰符检查通过后，才会被存储在 中： 上述两个检查分支都会跳转到 标签处，而该标签在返回前没有释放任何资源。此错误处理流程会回溯到 ，后者调用 进而调用 。然而， 仅通过遍历 来访问字段。那些从未被存入 的字段将无法被访问到，从而导致泄漏。 提交 （
Possible ATT&CK Techniques 1 AI
T1496 · Resource HijackingAffected Version Matrix 17
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Linux | Linux | 7403630eb94c1d664fb873f967427ef2f6ee3699< a2652fcf96b63e9da04951e4e58e6a0672df695d |
affected |
e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c< 3d42fed18b2c5707b6332ebe87b789fd768eb01b |
affected | ||
e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c< e787361bb6b0026ea3eb4d3fa7a304c7fcb99555 |
affected | ||
e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c< b22dc0add7d72b8bd9cae3188db0dd65da1c8652 |
affected | ||
e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c< 891c21f6d5673b2a519b536243bfc6dd2d35beb6 |
affected | ||
e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c< 230234d12ce42ab04132a32c3a848f07a5d27a71 |
affected | ||
8d505d06d7330f5d67d3e5e9e1c647fb0b10ddad |
affected | ||
6.1.33< 6.1.189 |
affected | ||
| … +9 more rows | |||
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I. Basic Information for CVE-2026-97921
Vulnerability Information
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Vulnerability Title
tracing: Free histogram the field rejected for a bad modifier
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Affected Products
II. Public POCs for CVE-2026-97921
| # | POC Description | Source Link | Shenlong Link |
|---|
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Patches & Fixes for CVE-2026-97921 (6)
Same Patch Batch · Linux · 2026-09-25 · 372 CVEs total
| CVE-2026-100075 | 9.8 CRITICAL | RDMA/srpt: Fix srpt_alloc_rw_ctxs() unwind counters |
| CVE-2026-97555 | 8.8 HIGH | smb: client: fix heap overflow in DACL owner/group rewrite |
| CVE-2026-97957 | 8.8 HIGH | net: hinic: fix mailbox segment buffer overflow |
| CVE-2026-97527 | 8.8 HIGH | scsi: qla2xxx: Serialize NVMe unsol ctx list with a per-fcport lock |
| CVE-2026-97528 | 8.8 HIGH | scsi: qla2xxx: Unlink NVMe unsol ctx before freeing on LS reject error |
| CVE-2026-98115 | 8.8 HIGH | ksmbd: safely drain sessions during logoff |
| CVE-2026-97525 | 8.2 HIGH | x86/mm/pat: Allocate split page tables as kernel page tables |
| CVE-2026-98069 | 8.1 HIGH | net/rds: acquire the fastpath locks in rds_conn_shutdown() |
| CVE-2026-97573 | 8.1 HIGH | bnxt_en: Handle buffer allocation failure in bnxt_rx_ring_reset() |
| CVE-2026-97570 | 8.1 HIGH | bnxt_en: Bound SW TPA IDs to prevent crashes |
| CVE-2026-98130 | 8.1 HIGH | sctp: fix a TOCTOU race in SCTP_CMD_TIMER_START |
| CVE-2026-98070 | 8.1 HIGH | net/rds: acquire RDS_IN_XMIT in rds_tcp_reset_callbacks() |
| CVE-2026-98122 | 7.8 HIGH | vxlan: mdb: Fix use-after-free in vxlan_mdb_remote_src_del() |
| CVE-2026-97575 | 7.8 HIGH | media: v4l2-ctrls: validate AV1 tile counts |
| CVE-2026-97576 | 7.8 HIGH | media: v4l2-ctrls: validate HEVC tile counts |
| CVE-2026-98112 | 7.8 HIGH | ksmbd: fix listener task lifetime on netdev events |
| CVE-2026-98002 | 7.8 HIGH | iommu/amd: Fix ineffective error check in nested domain allocation |
| CVE-2026-98116 | 7.8 HIGH | ALSA: pcm: Serialize PCM mmap with buffer reallocation to fix page UAF |
| CVE-2026-97580 | 7.8 HIGH | media: rkvdec: bound HEVC tile loops and PPS id to the array capacity |
| CVE-2026-97940 | 7.8 HIGH | ipv6: fix fib6 walker UAF on seq stop |
Showing top 20 of 372 CVEs. View all on vendor page → →
IV. Related Vulnerabilities
Same product: Linux
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CVE-2026-98382
bpf: Reject dev-bound-only programs on other devices -
CVE-2026-98381
veth: manage XDP program pointers during channel resize -
CVE-2026-98380
net/sched: reject IDR error pointers when deleting actions
Same vendor: Linux
-
CVE-2026-98384
bpf: Fix out-of-bounds read of sk_protocol in bpf_sock_destr -
CVE-2026-98383
bpf: Disallow bpf_skb_pull_data() for LWT_SEG6LOCAL -
CVE-2026-98382
bpf: Reject dev-bound-only programs on other devices -
CVE-2026-98381
veth: manage XDP program pointers during channel resize -
CVE-2026-98380
net/sched: reject IDR error pointers when deleting actions
V. Comments for CVE-2026-97921
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