First published: Fri Dec 06 2024(Updated: )
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.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Software | Affected Version | How to fix |
---|---|---|
Linux Kernel | >=2.6.12<4.19.325 | |
Linux Kernel | >=4.20<6.6.64 | |
Linux Kernel | >=6.7<6.11.11 | |
Linux Kernel | >=6.12<6.12.2 | |
debian/linux | <=5.10.223-1 | 5.10.234-1 6.1.129-1 6.1.128-1 6.12.20-1 6.12.21-1 |
debian/linux-6.1 | 6.1.129-1~deb11u1 |
Sign up to SecAlerts for real-time vulnerability data matched to your software, aggregated from hundreds of sources.
CVE-2024-53142 is classified with a medium severity rating due to its potential for a filename buffer overrun in the Linux kernel.
To fix CVE-2024-53142, you need to update the affected Linux kernel to a version that includes the patch for this vulnerability.
CVE-2024-53142 affects Linux kernel versions from 2.6.12 to 4.19.325, 4.20 to 6.6.64, 6.7 to 6.11.11, and 6.12 to 6.12.2.
CVE-2024-53142 is a buffer overrun vulnerability that can be exploited through improperly managed filename fields in initramfs.
No specific workaround for CVE-2024-53142 is recommended; the advised action is to apply the appropriate kernel updates.