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ext2: Fix fs corruption in ext2_get_xip_mem()

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commit 7ba3ec5749 upstream.

Commit 8e3dffc651 "Ext2: mark inode dirty after the function
dquot_free_block_nodirty is called" unveiled a bug in __ext2_get_block()
called from ext2_get_xip_mem(). That function called ext2_get_block()
mistakenly asking it to map 0 blocks while 1 was intended. Before the
above mentioned commit things worked out fine by luck but after that commit
we started returning that we allocated 0 blocks while we in fact
allocated 1 block and thus allocation was looping until all blocks in
the filesystem were exhausted.

Fix the problem by properly asking for one block and also add assertion
in ext2_get_blocks() to catch similar problems.

Reported-and-tested-by: Andiry Xu <andiry.xu@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Zefan Li <lizefan@huawei.com>
This commit is contained in:
Jan Kara 2013-11-05 01:15:38 +01:00 committed by Zefan Li
parent f79bb94b5a
commit 3a8f61352a
2 changed files with 3 additions and 0 deletions
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2
fs/ext2/inode.c
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@ -614,6 +614,8 @@ static int ext2_get_blocks(struct inode *inode,
int count = 0;
ext2_fsblk_t first_block = 0;
BUG_ON(maxblocks == 0);
depth = ext2_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
if (depth == 0)

1
fs/ext2/xip.c
View file

@ -35,6 +35,7 @@ __ext2_get_block(struct inode *inode, pgoff_t pgoff, int create,
int rc;
memset(&tmp, 0, sizeof(struct buffer_head));
tmp.b_size = 1 << inode->i_blkbits;
rc = ext2_get_block(inode, pgoff, &tmp, create);
*result = tmp.b_blocknr;