f2fs: fix to do sanity check in update_sit_entry

If GET_SEGNO return NULL_SEGNO for some unecpected case,
update_sit_entry will access invalid memory address,
cause system crash. It is better to do sanity check about
GET_SEGNO just like update_segment_mtime & locate_dirty_segment.

Also remove some redundant judgment code.

Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index fa395801137b7ed9a66f252ed9c95acfa80d23e3..0d21ce615cecd9f5b99b03effed7e682265f2865 100644 (file)
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -2413,6 +2413,8 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
 #endif
 
        segno = GET_SEGNO(sbi, blkaddr);
+       if (segno == NULL_SEGNO)
+               return;
 
        se = get_seg_entry(sbi, segno);
        new_vblocks = se->valid_blocks + del;
@@ -3526,8 +3528,7 @@ int f2fs_allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
         * since SSR needs latest valid block information.
         */
        update_sit_entry(sbi, *new_blkaddr, 1);
-       if (GET_SEGNO(sbi, old_blkaddr) != NULL_SEGNO)
-               update_sit_entry(sbi, old_blkaddr, -1);
+       update_sit_entry(sbi, old_blkaddr, -1);
 
        /*
         * If the current segment is full, flush it out and replace it with a