CVE-2024-53142: initramfs: avoid filename buffer overrun

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. ---- 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 products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < bb7ac96670ab1d8d681015f9d66e45dad579af4daffected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < c509b1acbd867d9e09580fe059a924cb5825afb1affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < d3df9f26cff97beaa5643e551031795d5d5cddbeaffected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < 6983b8ac787b3add5571cda563574932a59a99bbaffected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < f892ddcf9f645380c358e73653cb0900f6bc9eb8affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < 1a423bbbeaf9e3e20c4686501efd9b661fe834dbaffected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < 49d01e736c3045319e030d1e75fb983011abaca7affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < fb83b093f75806333b6f4ae29b158d2e0e3ec971affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < e017671f534dd3f568db9e47b0583e853d2da9b5affected

Linux Linux

Default version status: affected

2.6.12affected
0 to < 2.6.12unaffected
4.19.325 to ≤ 4.19.*unaffected
5.4.287 to ≤ 5.4.*unaffected
5.10.231 to ≤ 5.10.*unaffected
5.15.174 to ≤ 5.15.*unaffected
6.1.120 to ≤ 6.1.*unaffected
6.6.64 to ≤ 6.6.*unaffected
6.11.11 to ≤ 6.11.*unaffected
6.12.2 to ≤ 6.12.*unaffected
6.13 to ≤ *unaffected

CVE-2024-53142

initramfs: avoid filename buffer overrun

Description

Affected products

Linux Linux

Linux Linux

References