CVE-2024-50015

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

ext4: dax: fix overflowing extents beyond inode size when partially writing

The dax_iomap_rw() does two things in each iteration: map written blocks

and copy user data to blocks. If the process is killed by user(See signal

handling in dax_iomap_iter()), the copied data will be returned and added

on inode size, which means that the length of written extents may exceed

the inode size, then fsck will fail. An example is given as:

dd if=/dev/urandom of=file bs=4M count=1

dax_iomap_rw

iomap_iter // round 1

ext4_iomap_begin

ext4_iomap_alloc // allocate 0~2M extents(written flag)

dax_iomap_iter // copy 2M data

iomap_iter // round 2

iomap_iter_advance

iter->pos += iter->processed // iter->pos = 2M

ext4_iomap_begin

ext4_iomap_alloc // allocate 2~4M extents(written flag)

dax_iomap_iter

fatal_signal_pending

done = iter->pos - iocb->ki_pos // done = 2M

ext4_handle_inode_extension

ext4_updat

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References