bpf: Reject >8 byte return values on return-reading trampoline paths
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().
CVE-2026-90359
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-90359
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "fec56f5890d93fc2ed74166c397dc186b1c25951",
"lessThan": "de54ba33690d2dd3c4aa686c9693505644285b0b",
"versionType": "git"
},
{
"status": "affected",
"version": "fec56f5890d93fc2ed74166c397dc186b1c25951",
"lessThan": "9a9e902bd0556052534641f7d5f868c6dc4b84ae",
"versionType": "git"
},
{
"status": "affected",
"version": "fec56f5890d93fc2ed74166c397dc186b1c25951",
"lessThan": "d36ac53fc83baf843c51b7afd6d2471f36b713d8",
"versionType": "git"
},
{
"status": "affected",
"version": "fec56f5890d93fc2ed74166c397dc186b1c25951",
"lessThan": "c48796aa6c392cde93946e5d5a9a1f1b1cf72feb",
"versionType": "git"
}
],
"programFiles": [
"kernel/bpf/bpf_struct_ops.c",
"kernel/bpf/verifier.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.5"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.5",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.114",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.57",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"kernel/bpf/bpf_struct_ops.c",
"kernel/bpf/verifier.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-90359
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #48675 · Revision 1
- Added to Heist Feed
- Publisher date