ghsa-q56w-m7h5-j43f
Vulnerability from github
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
include
include
include
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
{
"affected": [],
"aliases": [
"CVE-2024-53111"
],
"database_specific": {
"cwe_ids": [
"CWE-190"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-12-02T14:15:11Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/mremap: fix address wraparound in move_page_tables()\n\nOn 32-bit platforms, it is possible for the expression `len + old_addr \u003c\nold_end` to be false-positive if `len + old_addr` wraps around. \n`old_addr` is the cursor in the old range up to which page table entries\nhave been moved; so if the operation succeeded, `old_addr` is the *end* of\nthe old region, and adding `len` to it can wrap.\n\nThe overflow causes mremap() to mistakenly believe that PTEs have been\ncopied; the consequence is that mremap() bails out, but doesn\u0027t move the\nPTEs back before the new VMA is unmapped, causing anonymous pages in the\nregion to be lost. So basically if userspace tries to mremap() a\nprivate-anon region and hits this bug, mremap() will return an error and\nthe private-anon region\u0027s contents appear to have been zeroed.\n\nThe idea of this check is that `old_end - len` is the original start\naddress, and writing the check that way also makes it easier to read; so\nfix the check by rearranging the comparison accordingly.\n\n(An alternate fix would be to refactor this function by introducing an\n\"orig_old_start\" variable or such.)\n\n\nTested in a VM with a 32-bit X86 kernel; without the patch:\n\n```\nuser@horn:~/big_mremap$ cat test.c\n#define _GNU_SOURCE\n#include \u003cstdlib.h\u003e\n#include \u003cstdio.h\u003e\n#include \u003cerr.h\u003e\n#include \u003csys/mman.h\u003e\n\n#define ADDR1 ((void*)0x60000000)\n#define ADDR2 ((void*)0x10000000)\n#define SIZE 0x50000000uL\n\nint main(void) {\n unsigned char *p1 = mmap(ADDR1, SIZE, PROT_READ|PROT_WRITE,\n MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED_NOREPLACE, -1, 0);\n if (p1 == MAP_FAILED)\n err(1, \"mmap 1\");\n unsigned char *p2 = mmap(ADDR2, SIZE, PROT_NONE,\n MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED_NOREPLACE, -1, 0);\n if (p2 == MAP_FAILED)\n err(1, \"mmap 2\");\n *p1 = 0x41;\n printf(\"first char is 0x%02hhx\\n\", *p1);\n unsigned char *p3 = mremap(p1, SIZE, SIZE,\n MREMAP_MAYMOVE|MREMAP_FIXED, p2);\n if (p3 == MAP_FAILED) {\n printf(\"mremap() failed; first char is 0x%02hhx\\n\", *p1);\n } else {\n printf(\"mremap() succeeded; first char is 0x%02hhx\\n\", *p3);\n }\n}\nuser@horn:~/big_mremap$ gcc -static -o test test.c\nuser@horn:~/big_mremap$ setarch -R ./test\nfirst char is 0x41\nmremap() failed; first char is 0x00\n```\n\nWith the patch:\n\n```\nuser@horn:~/big_mremap$ setarch -R ./test\nfirst char is 0x41\nmremap() succeeded; first char is 0x41\n```",
"id": "GHSA-q56w-m7h5-j43f",
"modified": "2024-12-11T21:31:57Z",
"published": "2024-12-02T15:31:39Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-53111"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/909543dc279a91122fb08e4653a72b82f0ad28f4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a4a282daf1a190f03790bf163458ea3c8d28d217"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.