From: Jan Kara Date: Tue, 5 Nov 2013 00:15:38 +0000 (+0100) Subject: ext2: Fix fs corruption in ext2_get_xip_mem() X-Git-Tag: firefly_0821_release~3679^2~1411 X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=b4644ca460891d3b5a841c99dee1d7d218eed71e;p=firefly-linux-kernel-4.4.55.git ext2: Fix fs corruption in ext2_get_xip_mem() 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 Signed-off-by: Jan Kara Cc: Wang Nan Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c index 0a87bb10998d..99d84ce038b8 100644 --- a/fs/ext2/inode.c +++ b/fs/ext2/inode.c @@ -632,6 +632,8 @@ 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 1c3312858fcf..e98171a11cfe 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;