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ext4: mballoc: fix possible NULL ptr & remove BUG_ONs from DOUBLE_CHECK

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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).

Link: https://lore.kernel.org/r/9a54f8a696ff17c057cd571be3d15ac3ec1407f1.1589086800.git.riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Ritesh Harjani 2020-05-10 11:54:49 +05:30 committed by Theodore Ts'o
parent a345021553
commit eb2b8ebb86
1 changed files with 9 additions and 2 deletions
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11
fs/ext4/mballoc.c
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@ -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);