f2fs: fix to do sanity check on segment bitmap of LFS curseg

As Jungyeon Reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=203233

- Reproduces
gcc poc_13.c
./run.sh f2fs

- Kernel messages
 F2FS-fs (sdb): Bitmap was wrongly set, blk:4608
 kernel BUG at fs/f2fs/segment.c:2133!
 RIP: 0010:update_sit_entry+0x35d/0x3e0
 Call Trace:
  f2fs_allocate_data_block+0x16c/0x5a0
  do_write_page+0x57/0x100
  f2fs_do_write_node_page+0x33/0xa0
  __write_node_page+0x270/0x4e0
  f2fs_sync_node_pages+0x5df/0x670
  f2fs_write_checkpoint+0x364/0x13a0
  f2fs_sync_fs+0xa3/0x130
  f2fs_do_sync_file+0x1a6/0x810
  do_fsync+0x33/0x60
  __x64_sys_fsync+0xb/0x10
  do_syscall_64+0x43/0x110
  entry_SYSCALL_64_after_hwframe+0x44/0xa9

The testcase fails because that, in fuzzed image, current segment was
allocated with LFS type, its .next_blkoff should point to an unused
block address, but actually, its bitmap shows it's not. So during
allocation, f2fs crash when setting bitmap.

Introducing sanity_check_curseg() to check such inconsistence of
current in-used segment.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 5f6e4cd..a034e0d 100644 (file)
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -4239,6 +4239,41 @@ static int build_dirty_segmap(struct f2fs_sb_info *sbi)
        return init_victim_secmap(sbi);
 }
 
+static int sanity_check_curseg(struct f2fs_sb_info *sbi)
+{
+       int i;
+
+       /*
+        * In LFS/SSR curseg, .next_blkoff should point to an unused blkaddr;
+        * In LFS curseg, all blkaddr after .next_blkoff should be unused.
+        */
+       for (i = 0; i < NO_CHECK_TYPE; i++) {
+               struct curseg_info *curseg = CURSEG_I(sbi, i);
+               struct seg_entry *se = get_seg_entry(sbi, curseg->segno);
+               unsigned int blkofs = curseg->next_blkoff;
+
+               if (f2fs_test_bit(blkofs, se->cur_valid_map))
+                       goto out;
+
+               if (curseg->alloc_type == SSR)
+                       continue;
+
+               for (blkofs += 1; blkofs < sbi->blocks_per_seg; blkofs++) {
+                       if (!f2fs_test_bit(blkofs, se->cur_valid_map))
+                               continue;
+out:
+                       f2fs_msg(sbi->sb, KERN_ERR,
+                               "Current segment's next free block offset is "
+                               "inconsistent with bitmap, logtype:%u, "
+                               "segno:%u, type:%u, next_blkoff:%u, blkofs:%u",
+                               i, curseg->segno, curseg->alloc_type,
+                               curseg->next_blkoff, blkofs);
+                       return -EINVAL;
+               }
+       }
+       return 0;
+}
+
 /*
  * Update min, max modified time for cost-benefit GC algorithm
  */
@@ -4334,6 +4369,10 @@ int f2fs_build_segment_manager(struct f2fs_sb_info *sbi)
        if (err)
                return err;
 
+       err = sanity_check_curseg(sbi);
+       if (err)
+               return err;
+
        init_min_max_mtime(sbi);
        return 0;
 }