CVE-2024-56619

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

nilfs2: fix potential out-of-bounds memory access in nilfs_find_entry()

Syzbot reported that when searching for records in a directory where the inodes i_size is corrupted and has a large value, memory access outside the folio/page range may occur, or a use-after-free bug may be detected if KASAN is enabled.

This is because nilfs_last_byte(), which is called by nilfs_find_entry() and others to calculate the number of valid bytes of directory data in a page from i_size and the page index, loses the upper 32 bits of the 64-bit size information due to an inappropriate type of local variable to which the i_size value is assigned.

This caused a large byte offset value due to underflow in the end address calculation in the calling nilfs_find_entry(), resulting in memory access that exceeds the folio/page size.

Fix this issue by changing the type of the local variable causing the bit loss from unsigned int to u64. The return value of nilfs_last_byte() is also of type unsigned int, but it is truncated so as not to exceed PAGE_SIZE and no bit loss occurs, so no change is required.

Affected Software

References

• https://git.kernel.org/stable/c/09d6d05579fd46e61abf6e457bb100ff11f3a9d3
• https://git.kernel.org/stable/c/31f7b57a77d4c82a34ddcb6ff35b5aa577ef153e
• https://git.kernel.org/stable/c/48eb6e7404948032bbe811c5affbe39f6b316951
• https://git.kernel.org/stable/c/5af8366625182f01f6d8465c9a3210574673af57
• https://git.kernel.org/stable/c/985ebec4ab0a28bb5910c3b1481a40fbf7f9e61d
• https://git.kernel.org/stable/c/c3afea07477baccdbdec4483f8d5e59d42a3f67f
• https://git.kernel.org/stable/c/e3732102a9d638d8627d14fdf7b208462f0520e0