CVE-2025-38218

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> f2fs: fix to do sanity check on sit_bitmap_size<br /> <br /> w/ below testcase, resize will generate a corrupted image which<br /> contains inconsistent metadata, so when mounting such image, it<br /> will trigger kernel panic:<br /> <br /> touch img<br /> truncate -s $((512*1024*1024*1024)) img<br /> mkfs.f2fs -f img $((256*1024*1024))<br /> resize.f2fs -s -i img -t $((1024*1024*1024))<br /> mount img /mnt/f2fs<br /> <br /> ------------[ cut here ]------------<br /> kernel BUG at fs/f2fs/segment.h:863!<br /> Oops: invalid opcode: 0000 [#1] SMP PTI<br /> CPU: 11 UID: 0 PID: 3922 Comm: mount Not tainted 6.15.0-rc1+ #191 PREEMPT(voluntary)<br /> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014<br /> RIP: 0010:f2fs_ra_meta_pages+0x47c/0x490<br /> <br /> Call Trace:<br /> f2fs_build_segment_manager+0x11c3/0x2600<br /> f2fs_fill_super+0xe97/0x2840<br /> mount_bdev+0xf4/0x140<br /> legacy_get_tree+0x2b/0x50<br /> vfs_get_tree+0x29/0xd0<br /> path_mount+0x487/0xaf0<br /> __x64_sys_mount+0x116/0x150<br /> do_syscall_64+0x82/0x190<br /> entry_SYSCALL_64_after_hwframe+0x76/0x7e<br /> RIP: 0033:0x7fdbfde1bcfe<br /> <br /> The reaseon is:<br /> <br /> sit_i-&gt;bitmap_size is 192, so size of sit bitmap is 192*8=1536, at maximum<br /> there are 1536 sit blocks, however MAIN_SEGS is 261893, so that sit_blk_cnt<br /> is 4762, build_sit_entries() -&gt; current_sit_addr() tries to access<br /> out-of-boundary in sit_bitmap at offset from [1536, 4762), once sit_bitmap<br /> and sit_bitmap_mirror is not the same, it will trigger f2fs_bug_on().<br /> <br /> Let&amp;#39;s add sanity check in f2fs_sanity_check_ckpt() to avoid panic.