Messages in this thread Patch in this message | | | From | Zefan Li <> | Subject | [PATCH 3.4 44/45] ext2: Fix fs corruption in ext2_get_xip_mem() | Date | Tue, 23 Sep 2014 10:31:46 +0800 |
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From: Jan Kara <jack@suse.cz>
3.4.104-rc1 review patch. If anyone has any objections, please let me know.
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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> Cc: Wang Nan <wangnan0@huawei.com> Signed-off-by: Zefan Li <lizefan@huawei.com> --- fs/ext2/inode.c | 2 ++ fs/ext2/xip.c | 1 + 2 files changed, 3 insertions(+)
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c index 740cad8..6a7c483 100644 --- a/fs/ext2/inode.c +++ b/fs/ext2/inode.c @@ -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) diff --git a/fs/ext2/xip.c b/fs/ext2/xip.c index 1c33128..e98171a 100644 --- a/fs/ext2/xip.c +++ b/fs/ext2/xip.c @@ -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; -- 1.7.9.5
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