2022-02-16 08:11:48

by Ritesh Harjani

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Subject: [PATCHv2 9/9] ext4: Add extra check in ext4_mb_mark_bb() to prevent against possible corruption

This patch adds an extra checks in ext4_mb_mark_bb() function
to make sure we mark & report error if we were to mark/clear any
of the critical FS metadata specific bitmaps (&bail out) to prevent
from any accidental corruption.

Suggested-by: Jan Kara <[email protected]>
Signed-off-by: Ritesh Harjani <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
---
fs/ext4/mballoc.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 0a95bdb1e07b..5f0bc6d0aabe 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3918,6 +3918,14 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
EXT4_BLOCKS_PER_GROUP(sb) - EXT4_C2B(sbi, blkoff));
clen = EXT4_NUM_B2C(sbi, thisgrp_len);

+ if (!ext4_sb_block_valid(sb, NULL, block, thisgrp_len)) {
+ ext4_error(sb, "Marking blocks in system zone - "
+ "Block = %llu, len = %u",
+ block, thisgrp_len);
+ bitmap_bh = NULL;
+ break;
+ }
+
bitmap_bh = ext4_read_block_bitmap(sb, group);
if (IS_ERR(bitmap_bh)) {
err = PTR_ERR(bitmap_bh);
--
2.31.1