ghsa-73xg-5c69-2755
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
initramfs: avoid filename buffer overrun
The initramfs filename field is defined in Documentation/driver-api/early-userspace/buffer-format.rst as:
37 cpio_file := ALGN(4) + cpio_header + filename + "\0" + ALGN(4) + data ... 55 ============= ================== ========================= 56 Field name Field size Meaning 57 ============= ================== ========================= ... 70 c_namesize 8 bytes Length of filename, including final \0
When extracting an initramfs cpio archive, the kernel's do_name() path handler assumes a zero-terminated path at @collected, passing it directly to filp_open() / init_mkdir() / init_mknod().
If a specially crafted cpio entry carries a non-zero-terminated filename and is followed by uninitialized memory, then a file may be created with trailing characters that represent the uninitialized memory. The ability to create an initramfs entry would imply already having full control of the system, so the buffer overrun shouldn't be considered a security vulnerability.
Append the output of the following bash script to an existing initramfs and observe any created /initramfs_test_fname_overrunAA* path. E.g. ./reproducer.sh | gzip >> /myinitramfs
It's easiest to observe non-zero uninitialized memory when the output is gzipped, as it'll overflow the heap allocated @out_buf in __gunzip(), rather than the initrd_start+initrd_size block.
---- reproducer.sh ---- nilchar="A" # change to "\0" to properly zero terminate / pad magic="070701" ino=1 mode=$(( 0100777 )) uid=0 gid=0 nlink=1 mtime=1 filesize=0 devmajor=0 devminor=1 rdevmajor=0 rdevminor=0 csum=0 fname="initramfs_test_fname_overrun" namelen=$(( ${#fname} + 1 )) # plus one to account for terminator
printf "%s%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%s" \ $magic $ino $mode $uid $gid $nlink $mtime $filesize \ $devmajor $devminor $rdevmajor $rdevminor $namelen $csum $fname
termpadlen=$(( 1 + ((4 - ((110 + $namelen) & 3)) % 4) )) printf "%.s${nilchar}" $(seq 1 $termpadlen) ---- reproducer.sh ----
Symlink filename fields handled in do_symlink() won't overrun past the data segment, due to the explicit zero-termination of the symlink target.
Fix filename buffer overrun by aborting the initramfs FSM if any cpio entry doesn't carry a zero-terminator at the expected (name_len - 1) offset.
{
"affected": [],
"aliases": [
"CVE-2024-53142"
],
"database_specific": {
"cwe_ids": [
"CWE-787"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-12-06T10:15:06Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ninitramfs: avoid filename buffer overrun\n\nThe initramfs filename field is defined in\nDocumentation/driver-api/early-userspace/buffer-format.rst as:\n\n 37 cpio_file := ALGN(4) + cpio_header + filename + \"\\0\" + ALGN(4) + data\n...\n 55 ============= ================== =========================\n 56 Field name Field size Meaning\n 57 ============= ================== =========================\n...\n 70 c_namesize 8 bytes Length of filename, including final \\0\n\nWhen extracting an initramfs cpio archive, the kernel\u0027s do_name() path\nhandler assumes a zero-terminated path at @collected, passing it\ndirectly to filp_open() / init_mkdir() / init_mknod().\n\nIf a specially crafted cpio entry carries a non-zero-terminated filename\nand is followed by uninitialized memory, then a file may be created with\ntrailing characters that represent the uninitialized memory. The ability\nto create an initramfs entry would imply already having full control of\nthe system, so the buffer overrun shouldn\u0027t be considered a security\nvulnerability.\n\nAppend the output of the following bash script to an existing initramfs\nand observe any created /initramfs_test_fname_overrunAA* path. E.g.\n ./reproducer.sh | gzip \u003e\u003e /myinitramfs\n\nIt\u0027s easiest to observe non-zero uninitialized memory when the output is\ngzipped, as it\u0027ll overflow the heap allocated @out_buf in __gunzip(),\nrather than the initrd_start+initrd_size block.\n\n---- reproducer.sh ----\nnilchar=\"A\"\t# change to \"\\0\" to properly zero terminate / pad\nmagic=\"070701\"\nino=1\nmode=$(( 0100777 ))\nuid=0\ngid=0\nnlink=1\nmtime=1\nfilesize=0\ndevmajor=0\ndevminor=1\nrdevmajor=0\nrdevminor=0\ncsum=0\nfname=\"initramfs_test_fname_overrun\"\nnamelen=$(( ${#fname} + 1 ))\t# plus one to account for terminator\n\nprintf \"%s%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%s\" \\\n\t$magic $ino $mode $uid $gid $nlink $mtime $filesize \\\n\t$devmajor $devminor $rdevmajor $rdevminor $namelen $csum $fname\n\ntermpadlen=$(( 1 + ((4 - ((110 + $namelen) \u0026 3)) % 4) ))\nprintf \"%.s${nilchar}\" $(seq 1 $termpadlen)\n---- reproducer.sh ----\n\nSymlink filename fields handled in do_symlink() won\u0027t overrun past the\ndata segment, due to the explicit zero-termination of the symlink\ntarget.\n\nFix filename buffer overrun by aborting the initramfs FSM if any cpio\nentry doesn\u0027t carry a zero-terminator at the expected (name_len - 1)\noffset.",
"id": "GHSA-73xg-5c69-2755",
"modified": "2024-12-14T21:31:34Z",
"published": "2024-12-06T12:30:47Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-53142"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1a423bbbeaf9e3e20c4686501efd9b661fe834db"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/49d01e736c3045319e030d1e75fb983011abaca7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6983b8ac787b3add5571cda563574932a59a99bb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bb7ac96670ab1d8d681015f9d66e45dad579af4d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c509b1acbd867d9e09580fe059a924cb5825afb1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d3df9f26cff97beaa5643e551031795d5d5cddbe"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e017671f534dd3f568db9e47b0583e853d2da9b5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f892ddcf9f645380c358e73653cb0900f6bc9eb8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fb83b093f75806333b6f4ae29b158d2e0e3ec971"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date |
|---|
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