In the Linux kernel, the following vulnerability has been resolved:
riscv: fix runtime constant support for nommu kernels
the `__runtime_fixup_32` function does not handle the case where `val` is
zero correctly (as might occur when patching a nommu kernel and referring
to a physical address below the 4GiB boundary whose upper 32 bits are all
zero) because nothing in the existing logic prevents the code from taking
the `else` branch of both nop-checks and emitting two `nop` instructions.
This leaves random garbage in the register that is supposed to receive the
upper 32 bits of the pointer instead of zero that when combined with the
value for the lower 32 bits yields an invalid pointer and causes a kernel
panic when that pointer is eventually accessed.
The author clearly considered the fact that if the `lui` is converted into
a `nop` that the second instruction needs to be adjusted to become an `li`
instead of an `addi`, hence introducing the `addi_insn_mask` variable, but
didn't follow that logic through fully to the case where the `else` branch
executes. To fix it just adjust the logic to ensure that the second `else`
branch is not taken if the first instruction will be patched to a `nop`.
CVSS
No CVSS.
References
Configurations
No configuration.
History
25 Jul 2025, 15:15
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2025-07-25 15:15
Updated : 2025-07-25 15:29
NVD link : CVE-2025-38433
Mitre link : CVE-2025-38433
CVE.ORG link : CVE-2025-38433
JSON object : View
Products Affected
No product.
CWE
No CWE.