CVE-2024-53111 mm/mremap: fix address wraparound in move_page_tables()

What is CVE-2024-53111?

CVE-2024-53111 is a high-severity vulnerability in Linux kernel, published on 2 Dec 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

mm/mremap: fix address wraparound in move_page_tables()

On 32-bit platforms, it is possible for the expression `len + old_addr < old_end` to be false-positive if `len + old_addr` wraps around. `old_addr` is the cursor in the old range up to which page table entries have been moved; so if the operation succeeded, `old_addr` is the *end* of the old region, and adding `len` to it can wrap.

The overflow causes mremap() to mistakenly believe that PTEs have been copied; the consequence is that mremap() bails out, but doesn't move the PTEs back before the new VMA is unmapped, causing anonymous pages in the region to be lost. So basically if userspace tries to mremap() a private-anon region and hits this bug, mremap() will return an error and the private-anon region's contents appear to have been zeroed.

The idea of this check is that `old_end - len` is the original start address, and writing the check that way also makes it easier to read; so fix the check by rearranging the comparison accordingly.

(An alternate fix would be to refactor this function by introducing an "orig_old_start" variable or such.)

Tested in a VM with a 32-bit X86 kernel; without the patch:

``` user@horn:~/big_mremap$ cat test.c #define _GNU_SOURCE #include <stdlib.h> #include <stdio.h> #include <err.h> #include <sys/mman.h>

#define ADDR1 ((void*)0x60000000) #define ADDR2 ((void*)0x10000000) #define SIZE 0x50000000uL

int main(void) { unsigned char *p1 = mmap(ADDR1, SIZE, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED_NOREPLACE, -1, 0); if (p1 == MAP_FAILED) err(1, "mmap 1"); unsigned char *p2 = mmap(ADDR2, SIZE, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED_NOREPLACE, -1, 0); if (p2 == MAP_FAILED) err(1, "mmap 2"); *p1 = 0x41; printf("first char is 0x%02hhx\n", *p1); unsigned char *p3 = mremap(p1, SIZE, SIZE, MREMAP_MAYMOVE|MREMAP_FIXED, p2); if (p3 == MAP_FAILED) { printf("mremap() failed; first char is 0x%02hhx\n", *p1); } else { printf("mremap() succeeded; first char is 0x%02hhx\n", *p3); } } user@horn:~/big_mremap$ gcc -static -o test test.c user@horn:~/big_mremap$ setarch -R ./test first char is 0x41 mremap() failed; first char is 0x00 ```

With the patch:

``` user@horn:~/big_mremap$ setarch -R ./test first char is 0x41 mremap() succeeded; first char is 0x41 ```

Weakness: CWE-190

Which versions are affected by CVE-2024-53111?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-53111?

Apply the vendor's patch.

Is CVE-2024-53111 being exploited?

There is no known exploitation of CVE-2024-53111 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2024-53111, DEBIAN-CVE-2024-53111, GHSA-q56w-m7h5-j43f, UBUNTU-CVE-2024-53111.