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CVE-2024-50194: arm64: probes: Fix uprobes for big-endian kernels

5.5 CVSS

Description

In the Linux kernel, the following vulnerability has been resolved:

arm64: probes: Fix uprobes for big-endian kernels

The arm64 uprobes code is broken for big-endian kernels as it doesn't
convert the in-memory instruction encoding (which is always
little-endian) into the kernel's native endianness before analyzing and
simulating instructions. This may result in a few distinct problems:

* The kernel may may erroneously reject probing an instruction which can
safely be probed.

* The kernel may erroneously erroneously permit stepping an
instruction out-of-line when that instruction cannot be stepped
out-of-line safely.

* The kernel may erroneously simulate instruction incorrectly dur to
interpretting the byte-swapped encoding.

The endianness mismatch isn't caught by the compiler or sparse because:

* The arch_uprobe::{insn,ixol} fields are encoded as arrays of u8, so
the compiler and sparse have no idea these contain a little-endian
32-bit value. The core uprobes code populates these with a memcpy()
which similarly does not handle endianness.

* While the uprobe_opcode_t type is an alias for __le32, both
arch_uprobe_analyze_insn() and arch_uprobe_skip_sstep() cast from u8[]
to the similarly-named probe_opcode_t, which is an alias for u32.
Hence there is no endianness conversion warning.

Fix this by changing the arch_uprobe::{insn,ixol} fields to __le32 and
adding the appropriate __le32_to_cpu() conversions prior to consuming
the instruction encoding...

Classification

CVE ID: CVE-2024-50194

CVSS Base Severity: MEDIUM

CVSS Base Score: 5.5

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.03% (probability of being exploited)

EPSS Percentile: 7.81% (scored less or equal to compared to others)

EPSS Date: 2025-06-02 (when was this score calculated)

References

Timeline

2025-05-04 10:40:22 UTC
CVE

arm64: probes: Fix uprobes for big-endian kernels