In the Linux kernel, the following vulnerability has been resolved:
bpf: Reject >8 byte return values on return-reading trampoline paths
btf_distill_func_proto() builds the function model used for the
fentry/fexit/fmod_ret/fsession trampolines and struct_ops. It has
accepted a 16-byte __int128 return value since the trampoline was
introduced: __get_type_size() returns the integer's type size, and the
return-type check only rejected ret < 0.
But the BPF trampoline preserves only 8 bytes of the return value (RAX on
x86, i.e. R0). For an attach type that reads the target's return value the
second half (RDX / R3) is neither saved nor restored, so a program
attached to a function returning a 16-byte value corrupts the value seen
by the real caller and itself observes only half of it. struct_ops
trampolines have the same limitation.
This affects the attach types that read the target's return value: fexit,
fmod_ret and fsession (plus the _multi variants of fexit and fsession),
and struct_ops. fentry/fentry_multi run before the target returns and are
unaffected.
Reject a >8 byte return value for these attach types in
bpf_check_attach_target() and bpf_check_attach_btf_id_multi(), and for
struct_ops in bpf_struct_ops_desc_init().
CVSS
No CVSS.
References
Configurations
No configuration.
History
17 Sep 2026, 17:17
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-09-17 17:17
Updated : 2026-09-17 17:17
NVD link : CVE-2026-90359
Mitre link : CVE-2026-90359
CVE.ORG link : CVE-2026-90359
JSON object : View
Products Affected
No product.
CWE
No CWE.