x86/cfi: Fix FineIBT hash offset in cfi_get_func_hash()
In the Linux kernel, the following vulnerability has been resolved: x86/cfi: Fix FineIBT hash offset in cfi_get_func_hash() The switch of the FineIBT preamble from "subl $hash, %r10d" to the shorter "subl $hash, %eax" moved the hash immediate from offset 7 to offset 5 of the preamble. fineibt_preamble_hash was updated to match, but the open-coded offset in cfi_get_func_hash() was missed and it still reads the hash at offset 7. cfi_get_func_hash() is used by the BPF JIT to give a struct_ops trampoline the CFI hash of the stub function it stands in for. With FineIBT the trampoline now gets the upper half of the real hash followed by the first two bytes of the next instruction, so the first indirect call from the kernel into a struct_ops program, tcp_init_congestion_control() calling ->init() of a BPF congestion control for example, fails the FineIBT check and the kernel dies with a CFI failure. Move the FineIBT preamble template and its offset defines above cfi_get_func_hash() and use fineibt_preamble_hash there, so every reader of the preamble shares one definition of its layout. The CFI_FINEIBT arm is only built with CONFIG_FINEIBT, the only configuration in which cfi_mode can take that value. cfi_get_func_arity() does not need the same treatment: the __bhi_args call whose displacement it reads still ends at the function address.
CVE-2026-97944
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-2026-97944
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": "85a2d4a890dce3cfc9c14aa91afc3dd7af8e3bf5",
"lessThan": "cd9b4595d6283f9b8a35d7ae607508de45a351ce",
"versionType": "git"
},
{
"status": "affected",
"version": "85a2d4a890dce3cfc9c14aa91afc3dd7af8e3bf5",
"lessThan": "67cf94c30a8b5ebc839f282f5c5a522b35903524",
"versionType": "git"
},
{
"status": "affected",
"version": "85a2d4a890dce3cfc9c14aa91afc3dd7af8e3bf5",
"lessThan": "5a5d26f2cfe13467166219f6bf58099326912ddb",
"versionType": "git"
}
],
"programFiles": [
"arch/x86/kernel/alternative.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.18"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.18",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.18.53",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.7",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"arch/x86/kernel/alternative.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-97944
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #38087 · Revision 1
- Added to Heist Feed
- Publisher date