CVE-2024-56692: Improper Check for Unusual or Exceptional Conditions

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

f2fs: fix to do sanity check on node blkaddr in truncate_node()

syzbot reports a f2fs bug as below:

------------[ cut here ]------------ kernel BUG at fs/f2fs/segment.c:2534! RIP: 0010:f2fs_invalidate_blocks+0x35f/0x370 fs/f2fs/segment.c:2534 Call Trace: truncate_node+0x1ae/0x8c0 fs/f2fs/node.c:909 f2fs_remove_inode_page+0x5c2/0x870 fs/f2fs/node.c:1288 f2fs_evict_inode+0x879/0x15c0 fs/f2fs/inode.c:856 evict+0x4e8/0x9b0 fs/inode.c:723 f2fs_handle_failed_inode+0x271/0x2e0 fs/f2fs/inode.c:986 f2fs_create+0x357/0x530 fs/f2fs/namei.c:394 lookup_open fs/namei.c:3595 [inline] open_last_lookups fs/namei.c:3694 [inline] path_openat+0x1c03/0x3590 fs/namei.c:3930 do_filp_open+0x235/0x490 fs/namei.c:3960 do_sys_openat2+0x13e/0x1d0 fs/open.c:1415 do_sys_open fs/open.c:1430 [inline] __do_sys_openat fs/open.c:1446 [inline] __se_sys_openat fs/open.c:1441 [inline] __x64_sys_openat+0x247/0x2a0 fs/open.c:1441 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0010:f2fs_invalidate_blocks+0x35f/0x370 fs/f2fs/segment.c:2534

The root cause is: on a fuzzed image, blkaddr in nat entry may be corrupted, then it will cause system panic when using it in f2fs_invalidate_blocks(), to avoid this, let's add sanity check on nat blkaddr in truncate_node().