In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Fix RxGK token loading to check bounds
rxrpc_preparse_xdr_yfs_rxgk() reads the raw key length and ticket length
from the XDR token as u32 values and passes each through round_up(x, 4)
before using the rounded value for validation and allocation. When the raw
length is >= 0xfffffffd, round_up() wraps to 0, so the bounds check and
kzalloc both use 0 while the subsequent memcpy still copies the original
~4 GiB value, producing a heap buffer overflow reachable from an
unprivileged add_key() call.
Fix this by:
(1) Rejecting raw key lengths above AFSTOKEN_GK_KEY_MAX and raw ticket
lengths above AFSTOKEN_GK_TOKEN_MAX before rounding, consistent with
the caps that the RxKAD path already enforces via AFSTOKEN_RK_TIX_MAX.
(2) Sizing the flexible-array allocation from the validated raw key
length via struct_size_t() instead of the rounded value.
(3) Caching the raw lengths so that the later field assignments and
memcpy calls do not re-read from the token, eliminating a class of
TOCTOU re-parse.
The control path (valid token with lengths within bounds) is unaffected.
rxrpc: Fix RxGK token loading to check bounds
rxrpc_preparse_xdr_yfs_rxgk() reads the raw key length and ticket length
from the XDR token as u32 values and passes each through round_up(x, 4)
before using the rounded value for validation and allocation. When the raw
length is >= 0xfffffffd, round_up() wraps to 0, so the bounds check and
kzalloc both use 0 while the subsequent memcpy still copies the original
~4 GiB value, producing a heap buffer overflow reachable from an
unprivileged add_key() call.
Fix this by:
(1) Rejecting raw key lengths above AFSTOKEN_GK_KEY_MAX and raw ticket
lengths above AFSTOKEN_GK_TOKEN_MAX before rounding, consistent with
the caps that the RxKAD path already enforces via AFSTOKEN_RK_TIX_MAX.
(2) Sizing the flexible-array allocation from the validated raw key
length via struct_size_t() instead of the rounded value.
(3) Caching the raw lengths so that the later field assignments and
memcpy calls do not re-read from the token, eliminating a class of
TOCTOU re-parse.
The control path (valid token with lengths within bounds) is unaffected.
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Sat, 25 Apr 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-190 | |
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Fri, 24 Apr 2026 15:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix RxGK token loading to check bounds rxrpc_preparse_xdr_yfs_rxgk() reads the raw key length and ticket length from the XDR token as u32 values and passes each through round_up(x, 4) before using the rounded value for validation and allocation. When the raw length is >= 0xfffffffd, round_up() wraps to 0, so the bounds check and kzalloc both use 0 while the subsequent memcpy still copies the original ~4 GiB value, producing a heap buffer overflow reachable from an unprivileged add_key() call. Fix this by: (1) Rejecting raw key lengths above AFSTOKEN_GK_KEY_MAX and raw ticket lengths above AFSTOKEN_GK_TOKEN_MAX before rounding, consistent with the caps that the RxKAD path already enforces via AFSTOKEN_RK_TIX_MAX. (2) Sizing the flexible-array allocation from the validated raw key length via struct_size_t() instead of the rounded value. (3) Caching the raw lengths so that the later field assignments and memcpy calls do not re-read from the token, eliminating a class of TOCTOU re-parse. The control path (valid token with lengths within bounds) is unaffected. | |
| Title | rxrpc: Fix RxGK token loading to check bounds | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-04-24T14:44:56.204Z
Reserved: 2026-03-09T15:48:24.126Z
Link: CVE-2026-31641
No data.
Status : Awaiting Analysis
Published: 2026-04-24T15:16:43.463
Modified: 2026-04-24T17:51:40.810
Link: CVE-2026-31641
OpenCVE Enrichment
No data.
Weaknesses