Make sure to check for e4b->bd_info->bb_bitmap == NULL, in
mb_cmp_bitmaps() and return if NULL, to avoid possible NULL ptr
dereference. Similar to how we do this in other ifdef DOUBLE_CHECK
functions.
Also remove the BUG_ON() logic if kmalloc() or ext4_read_block_bitmap()
fails. We should simply mark grp->bb_bitmap as NULL if above happens.
In fact ext4_read_block_bitmap() may even return an error in case of resize
ioctl. Hence remove this BUG_ON logic (fstests ext4/032 may trigger
this).
---
Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
---
fs/ext4/mballoc.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 3555e72f149c..c713d06e70b7 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -493,6 +493,8 @@ static void mb_mark_used_double(struct ext4_buddy *e4b, int first, int count)
static void mb_cmp_bitmaps(struct ext4_buddy *e4b, void *bitmap)
{
+ if (unlikely(e4b->bd_info->bb_bitmap == NULL))
+ return;
if (memcmp(e4b->bd_info->bb_bitmap, bitmap, e4b->bd_sb->s_blocksize)) {
unsigned char *b1, *b2;
int i;
@@ -517,10 +519,15 @@ static void mb_group_bb_bitmap_alloc(struct super_block *sb,
struct buffer_head *bh;
grp->bb_bitmap = kmalloc(sb->s_blocksize, GFP_NOFS);
- BUG_ON(grp->bb_bitmap == NULL);
+ if (!grp->bb_bitmap)
+ return;
bh = ext4_read_block_bitmap(sb, group);
- BUG_ON(IS_ERR_OR_NULL(bh));
+ if (IS_ERR_OR_NULL(bh)) {
+ kfree(grp->bb_bitmap);
+ grp->bb_bitmap = NULL;
+ return;
+ }
memcpy(grp->bb_bitmap, bh->b_data, sb->s_blocksize);
put_bh(bh);
--
2.21.0
