CVE-2024-42304: linux kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: ext4: make sure the first directory block is not a hole The syzbot constructs a directory that has no dirblock but is non-inline, i.e. the first directory block is a hole. And no errors are reported when creating files in this directory in the following flow. ext4_mknod ... ext4_add_entry // Read block 0 ext4_read_dirblock(dir, block, DIRENT) bh = ext4_bread(NULL, inode, block, 0) if (!bh && (type == INDEX || type == DIRENT_HTREE)) // The first directory block is a hole // But type == DIRENT, so no error is reported. After that, we get a directory block without '.' and '..' but with a valid dentry. This may cause some code that relies on dot or dotdot (such as make_indexed_dir()) to crash. Therefore when ext4_read_dirblock() finds that the first directory block is a hole report that the filesystem is corrupted and return an error to avoid loading corrupted data from disk causing something bad.
CVE-2024-42304CVSS 5.5Linux

CVE-2024-42304: linux kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: ext4: make sure the first directory block is not a hole The syzbot constructs a directory that has no dirblock but is non-inline, i.e. the first directory block is a hole. And no errors are reported when creating files in this directory in the following flow. ext4_mknod ... ext4_add_entry // Read block 0 ext4_read_dirblock(dir, block, DIRENT) bh = ext4_bread(NULL, inode, block, 0) if (!bh && (type == INDEX || type == DIRENT_HTREE)) // The first directory block is a hole // But type == DIRENT, so no error is reported. After that, we get a directory block without '.' and '..' but with a valid dentry. This may cause some code that relies on dot or dotdot (such as make_indexed_dir()) to crash. Therefore when ext4_read_dirblock() finds that the first directory block is a hole report that the filesystem is corrupted and return an error to avoid loading corrupted data from disk causing something bad.

CVSS
5.5 MEDIUM
EPSS
13%
Known exploited
not in KEV
Product
linux kernel

What is known

In the Linux kernel, the following vulnerability has been resolved: ext4: make sure the first directory block is not a hole The syzbot constructs a directory that has no dirblock but is non-inline, i.e. the first directory block is a hole. And no errors are reported when creating files in this directory in the following flow. ext4_mknod ... ext4_add_entry // Read block 0 ext4_read_dirblock(dir, block, DIRENT) bh = ext4_bread(NULL, inode, block, 0) if (!bh && (type == INDEX || type == DIRENT_HTREE)) // The first directory block is a hole // But type == DIRENT, so no error is reported. After that, we get a directory block without '.' and '..' but with a valid dentry. This may cause some code that relies on dot or dotdot (such as make_indexed_dir()) to crash. Therefore when ext4_read_dirblock() finds that the first directory block is a hole report that the filesystem is corrupted and return an error to avoid loading corrupted data from disk causing something bad.

Sources

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