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CVE-2024-50099: arm64: probes: Remove broken LDR (literal) uprobe support

5.5 CVSS

Description

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

arm64: probes: Remove broken LDR (literal) uprobe support

The simulate_ldr_literal() and simulate_ldrsw_literal() functions are
unsafe to use for uprobes. Both functions were originally written for
use with kprobes, and access memory with plain C accesses. When uprobes
was added, these were reused unmodified even though they cannot safely
access user memory.

There are three key problems:

1) The plain C accesses do not have corresponding extable entries, and
thus if they encounter a fault the kernel will treat these as
unintentional accesses to user memory, resulting in a BUG() which
will kill the kernel thread, and likely lead to further issues (e.g.
lockup or panic()).

2) The plain C accesses are subject to HW PAN and SW PAN, and so when
either is in use, any attempt to simulate an access to user memory
will fault. Thus neither simulate_ldr_literal() nor
simulate_ldrsw_literal() can do anything useful when simulating a
user instruction on any system with HW PAN or SW PAN.

3) The plain C accesses are privileged, as they run in kernel context,
and in practice can access a small range of kernel virtual addresses.
The instructions they simulate have a range of +/-1MiB, and since the
simulated instructions must itself be a user instructions in the
TTBR0 address range, these can address the final 1MiB of the TTBR1
acddress range by wrapping downwards from an address ...

Classification

CVE ID: CVE-2024-50099

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: 8.2% (scored less or equal to compared to others)

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

References

Timeline

2025-03-06 09:45:28 UTC
Tenable Plugins

Linux Distros Unpatched Vulnerability : CVE-2024-50099
2025-05-04 10:40:21 UTC
CVE

arm64: probes: Remove broken LDR (literal) uprobe support