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Commit d4620315 authored by Robin Dong's avatar Robin Dong Committed by Theodore Ts'o
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ext4: avoid eh_entries overflow before insert extent_idx 



If eh_entries is equal to (or greater than) eh_max, the operation of
inserting new extent_idx will make number of entries overflow.
So check eh_entries before inserting the new extent_idx.

Although there is no bug case according the code (function
ext4_ext_insert_index is called by ext4_ext_split and ext4_ext_split
is called only if the index block has free space), the right logic
should be "lookup the capacity before insertion".

Signed-off-by: default avatarRobin Dong <sanbai@taobao.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 015861ba

fs/ext4/extents.c

+10 −8
Original line number Diff line number Diff line
@@ -741,6 +741,16 @@ static int ext4_ext_insert_index(handle_t *handle, struct inode *inode, 
				 logical, le32_to_cpu(curp->p_idx->ei_block));

		return -EIO;

	}



	if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)

			     >= le16_to_cpu(curp->p_hdr->eh_max))) {

		EXT4_ERROR_INODE(inode,

				 "eh_entries %d >= eh_max %d!",

				 le16_to_cpu(curp->p_hdr->eh_entries),

				 le16_to_cpu(curp->p_hdr->eh_max));

		return -EIO;

	}



	len = EXT_MAX_INDEX(curp->p_hdr) - curp->p_idx;

	if (logical > le32_to_cpu(curp->p_idx->ei_block)) {

		/* insert after */
@@ -770,14 +780,6 @@ static int ext4_ext_insert_index(handle_t *handle, struct inode *inode, 
	ext4_idx_store_pblock(ix, ptr);

	le16_add_cpu(&curp->p_hdr->eh_entries, 1);



	if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)

			     > le16_to_cpu(curp->p_hdr->eh_max))) {

		EXT4_ERROR_INODE(inode,

				 "eh_entries %d > eh_max %d!",

				 le16_to_cpu(curp->p_hdr->eh_entries),

				 le16_to_cpu(curp->p_hdr->eh_max));

		return -EIO;

	}

	if (unlikely(ix > EXT_LAST_INDEX(curp->p_hdr))) {

		EXT4_ERROR_INODE(inode, "ix > EXT_LAST_INDEX!");

		return -EIO;