bpf, s390: Clear fetch destination on faulting arena atomic
Same missing register clear as on riscv64. A RMW atomic on an arena pointer
is converted to BPF_PROBE_ATOMIC and gets an exception table entry, but
bpf_jit_probe_atomic_pre() only fills in the arena base and the probe
offset, leaving probe->reg at the -1 that bpf_jit_probe_init() set, which
bpf_jit_probe_post() writes into the entry and ex_handler_bpf() then reads
back as "there is nothing to clear".
That is right for a plain BPF_{ADD,AND,OR,XOR}, which only writes memory,
but an RMW carrying BPF_FETCH also reads the old value into a register:
src_reg for BPF_{ADD,AND,OR,XOR} | BPF_FETCH and BPF_XCHG, and r0 for
BPF_CMPXCHG. So on a fault over an unmapped arena page the program resumes
at the landing pad with whatever that register held before the atomic
instead of the 0 that every other BPF_PROBE_* access delivers.
Fill probe->reg in from bpf_atomic_load_reg(). Unlike x86-64 and arm64,
s390x does not report arena violations from its exception handler, so there
is no access direction to correct here, only the missing register clear.
Analysis
Analysis and contextual insights are available on OpenCVE Cloud.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
||||||||||||||||||
| Linux | Linux | affected |
|
No data.
No data.
No data available yet.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
Sign in to view the affected projects.
No advisories yet.
Thu, 17 Sep 2026 16:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: bpf, s390: Clear fetch destination on faulting arena atomic Same missing register clear as on riscv64. A RMW atomic on an arena pointer is converted to BPF_PROBE_ATOMIC and gets an exception table entry, but bpf_jit_probe_atomic_pre() only fills in the arena base and the probe offset, leaving probe->reg at the -1 that bpf_jit_probe_init() set, which bpf_jit_probe_post() writes into the entry and ex_handler_bpf() then reads back as "there is nothing to clear". That is right for a plain BPF_{ADD,AND,OR,XOR}, which only writes memory, but an RMW carrying BPF_FETCH also reads the old value into a register: src_reg for BPF_{ADD,AND,OR,XOR} | BPF_FETCH and BPF_XCHG, and r0 for BPF_CMPXCHG. So on a fault over an unmapped arena page the program resumes at the landing pad with whatever that register held before the atomic instead of the 0 that every other BPF_PROBE_* access delivers. Fill probe->reg in from bpf_atomic_load_reg(). Unlike x86-64 and arm64, s390x does not report arena violations from its exception handler, so there is no access direction to correct here, only the missing register clear. | |
| Title | bpf, s390: Clear fetch destination on faulting arena atomic | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-17T16:07:25.454Z
Reserved: 2026-09-11T19:38:34.793Z
Link: CVE-2026-90211
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-17T17:17:16.330
Modified: 2026-09-17T17:17:16.330
Link: CVE-2026-90211
Redhat
No data.
OpenCVE Enrichment
No data.
No weakness.