Description

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.

-...

Classification

CVE ID: CVE-2024-53142

CVSS Base Severity: LOW

CVSS Base Score: 0.0

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 5.06% (scored less or equal to compared to others)

EPSS Date: 2025-02-03 (when was this score calculated)

References

https://git.kernel.org/stable/c/bb7ac96670ab1d8d681015f9d66e45dad579af4d
https://git.kernel.org/stable/c/49d01e736c3045319e030d1e75fb983011abaca7
https://git.kernel.org/stable/c/fb83b093f75806333b6f4ae29b158d2e0e3ec971
https://git.kernel.org/stable/c/e017671f534dd3f568db9e47b0583e853d2da9b5

Timeline