Description of problem:
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to do sanity check on i_xattr_nid in sanity_check_inode() syzbot reports a kernel bug as below: F2FS-fs (loop0): Mounted with checkpoint version = 48b305e4
==================================================================
BUG: KASAN: slab-out-of-bounds in f2fs_test_bit fs/f2fs/f2fs.h:2933 [inline]
BUG: KASAN: slab-out-of-bounds in current_nat_addr fs/f2fs/node.h:213 [inline]
BUG: KASAN: slab-out-of-bounds in f2fs_get_node_info+0xece/0x1200 fs/f2fs/node.c:600
Read of size 1 at addr ffff88807a58c76c by task syz-executor280/5076

CPU: 1 PID: 5076 Comm: syz-executor280 Not tainted 6.9.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 f2fs_test_bit fs/f2fs/f2fs.h:2933 [inline]
 current_nat_addr fs/f2fs/node.h:213 [inline]
 f2fs_get_node_info+0xece/0x1200 fs/f2fs/node.c:600
 f2fs_xattr_fiemap fs/f2fs/data.c:1848 [inline]
 f2fs_fiemap+0x55d/0x1ee0 fs/f2fs/data.c:1925
 ioctl_fiemap fs/ioctl.c:220 [inline]
 do_vfs_ioctl+0x1c07/0x2e50 fs/ioctl.c:838
 __do_sys_ioctl fs/ioctl.c:902 [inline]
 __se_sys_ioctl+0x81/0x170 fs/ioctl.c:890
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The root cause is we missed to do sanity check on i_xattr_nid during
f2fs_iget(), so that in fiemap() path, current_nat_addr() will access
nat_bitmap w/ offset from invalid i_xattr_nid, result in triggering
kasan bug report, fix it.

Version-Release number of selected component (if applicable):
Kernel version: 6.9.0-rc5

F2FS module: Part of the Linux kernel tree.

How reproducible:
Reproducibility: Likely reproducible under specific conditions where an invalid i_xattr_nid is present in the F2FS filesystem metadata.

Trigger: The bug is triggered when the fiemap ioctl is called on a file with corrupted or invalid extended attribute metadata.

Steps to Reproduce:
Set up a F2FS filesystem on a loop device or physical storage.

Corrupt the i_xattr_nid field in the filesystem metadata (e.g., using a custom tool or by inducing filesystem corruption).

Mount the F2FS filesystem.

Execute the fiemap ioctl on a file with the corrupted metadata.

Observe the KASAN bug report in the kernel logs.

Actual results:
The kernel triggers a KASAN slab-out-of-bounds bug report.

The call trace shows the issue originates in f2fs_get_node_info when accessing the nat_bitmap using an invalid i_xattr_nid.

The system may become unstable or crash depending on the severity of the memory corruption.

Expected results:
The kernel should handle invalid i_xattr_nid values gracefully, either by returning an error or ignoring the invalid metadata.

No out-of-bounds memory access should occur.

Additional info:
CVE ID:CVE-2024-39467
Vulnerability Description: For more detailed information about this vulnerability, please refer to the official Red Hat Security advisory page
https://access.redhat.com/security/cve/cve-2024-39467