| From | Ben Hutchings <> | Date | Sat, 01 Nov 2014 22:28:03 +0000 | Subject | [PATCH 3.2 099/102] ext2: Fix fs corruption in ext2_get_xip_mem() |
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3.2.64-rc1 review patch. If anyone has any objections, please let me know.
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From: Jan Kara <jack@suse.cz>
commit 7ba3ec5749ddb61f79f7be17b5fd7720eebc52de upstream.
Commit 8e3dffc651cb "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> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- fs/ext2/inode.c | 2 ++ fs/ext2/xip.c | 1 + 2 files changed, 3 insertions(+)
--- a/fs/ext2/inode.c +++ b/fs/ext2/inode.c @@ -619,6 +619,8 @@ static int ext2_get_blocks(struct 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) --- a/fs/ext2/xip.c +++ b/fs/ext2/xip.c @@ -37,6 +37,7 @@ __ext2_get_block(struct inode *inode, pg 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;
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