CVE-2024-50194: In the Linux kernel, the following vulnerability has been resolved: arm64: probes: Fix uprobes for big-endian kernels The arm64 uprobes code is brok...

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. The core uprobes copies these fields as opaque ranges of bytes, and so is unaffected by this change. At the same time, remove MAX_UINSN_BYTES and consistently use AARCH64_INSN_SIZE for clarity. Tested with the following: | #include <stdio.h> | #include <stdbool.h> | | #define noinline __attribute__((noinline)) | | static noinline void *adrp_self(void) | { | void *addr; | | asm volatile( | " adrp %x0, adrp_self\n" | " add %x0, %x0, :lo12:adrp_self\n" | : "=r" (addr)); | } | | | int main(int argc, char *argv) | { | void *ptr = adrp_self(); | bool equal = (ptr == adrp_self); | | printf("adrp_self => %p\n" | "adrp_self() => %p\n" | "%s\n", | adrp_self, ptr, equal ? "EQUAL" : "NOT EQUAL"); | | return 0; | } .... where the adrp_self() function was compiled to: | 00000000004007e0 <adrp_self>: | 4007e0: 90000000 adrp x0, 400000 <__ehdr_start> | 4007e4: 911f8000 add x0, x0, #0x7e0 | 4007e8: d65f03c0 ret Before this patch, the ADRP is not recognized, and is assumed to be steppable, resulting in corruption of the result: | # ./adrp-self | adrp_self => 0x4007e0 | adrp_self() => 0x4007e0 | EQUAL | # echo 'p /root/adrp-self:0x007e0' > /sys/kernel/tracing/uprobe_events | # echo 1 > /sys/kernel/tracing/events/uprobes/enable | # ./adrp-self | adrp_self => 0x4007e0 | adrp_self() => 0xffffffffff7e0 | NOT EQUAL After this patch, the ADRP is correctly recognized and simulated: | # ./adrp-self | adrp_self => 0x4007e0 | adrp_self() => 0x4007e0 | EQUAL | # | # echo 'p /root/adrp-self:0x007e0' > /sys/kernel/tracing/uprobe_events | # echo 1 > /sys/kernel/tracing/events/uprobes/enable | # ./adrp-self | adrp_self => 0x4007e0 | adrp_self() => 0x4007e0 | EQUAL

Metrics

CVSS 3.1

5.5/10

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

EPSS Probability

0.23%

13.6th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions	Update
Linux	Linux Kernel	>= 4.10, < 4.19.323	—
Linux	Linux Kernel	>= 4.20, < 5.4.285	—
Linux	Linux Kernel	>= 5.5, < 5.10.229	—
Linux	Linux Kernel	>= 5.11, < 5.15.170	—
Linux	Linux Kernel	>= 5.16, < 6.1.115	—
Linux	Linux Kernel	>= 6.2, < 6.6.58	—
Linux	Linux Kernel	>= 6.7, < 6.11.5	—
Linux	Linux Kernel	6.12	Rc1

References

Timeline

Published: Nov 8, 2024
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2024-50194?

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. The core uprobes copies these fields as opaque ranges of bytes, and so is unaffected by this change. At the same time, remove MAX_UINSN_BYTES and consistently use AARCH64_INSN_SIZE for clarity. Tested with the following: | #include <stdio.h> | #include <stdbool.h> | | #define noinline __attribute__((noinline)) | | static noinline void *adrp_self(void) | { | void *addr; | | asm volatile( | " adrp %x0, adrp_self\n" | " add %x0, %x0, :lo12:adrp_self\n" | : "=r" (addr)); | } | | | int main(int argc, char *argv) | { | void *ptr = adrp_self(); | bool equal = (ptr == adrp_self); | | printf("adrp_self => %p\n" | "adrp_self() => %p\n" | "%s\n", | adrp_self, ptr, equal ? "EQUAL" : "NOT EQUAL"); | | return 0; | } .... where the adrp_self() function was compiled to: | 00000000004007e0 <adrp_self>: | 4007e0: 90000000 adrp x0, 400000 <__ehdr_start> | 4007e4: 911f8000 add x0, x0, #0x7e0 | 4007e8: d65f03c0 ret Before this patch, the ADRP is not recognized, and is assumed to be steppable, resulting in corruption of the result: | # ./adrp-self | adrp_self => 0x4007e0 | adrp_self() => 0x4007e0 | EQUAL | # echo 'p /root/adrp-self:0x007e0' > /sys/kernel/tracing/uprobe_events | # echo 1 > /sys/kernel/tracing/events/uprobes/enable | # ./adrp-self | adrp_self => 0x4007e0 | adrp_self() => 0xffffffffff7e0 | NOT EQUAL After this patch, the ADRP is correctly recognized and simulated: | # ./adrp-self | adrp_self => 0x4007e0 | adrp_self() => 0x4007e0 | EQUAL | # | # echo 'p /root/adrp-self:0x007e0' > /sys/kernel/tracing/uprobe_events | # echo 1 > /sys/kernel/tracing/events/uprobes/enable | # ./adrp-self | adrp_self => 0x4007e0 | adrp_self() => 0x4007e0 | EQUAL

How severe is CVE-2024-50194?

CVE-2024-50194 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.23% probability of exploitation in the next 30 days.

How do I fix CVE-2024-50194?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.