[PATCH] ocfs2: zero-initialize recovery bitmap to prevent uninit-value in find_next_bit

[Daniel Hodges]

ocfs2_add_recovery_chunk() allocates a bitmap buffer of sb->s_blocksize
bytes using kmalloc() but only copies (ol_chunk_entries(sb) + 7) >> 3
bytes into it from the on-disk quota chunk. When the number of chunk
entries is not aligned to a long boundary (64 bits on 64-bit systems),
find_next_bit() reads uninitialized memory from the trailing bytes of
the last word in the bitmap.

Fix this by using kzalloc() to zero-initialize the entire bitmap
allocation, ensuring that any bits beyond the copied region are
clean zeros.

Reported-by: syzbot+7ea0b96c4ddb49fd1a70@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 2205363dce74 ("ocfs2: Implement quota recovery")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Daniel Hodges <git@xxxxxxxxxxxxxxxx>
---
 fs/ocfs2/quota_local.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
index de7f12858729..bd3eb098097f 100644
--- a/fs/ocfs2/quota_local.c
+++ b/fs/ocfs2/quota_local.c
@@ -302,7 +302,7 @@ static int ocfs2_add_recovery_chunk(struct super_block *sb,
 	if (!rc)
 		return -ENOMEM;
 	rc->rc_chunk = chunk;
-	rc->rc_bitmap = kmalloc(sb->s_blocksize, GFP_NOFS);
+	rc->rc_bitmap = kzalloc(sb->s_blocksize, GFP_NOFS);
 	if (!rc->rc_bitmap) {
 		kfree(rc);
 		return -ENOMEM;
-- 
2.52.0