Commit c37336b0 authored by Evgeniy Dushistov's avatar Evgeniy Dushistov Committed by Linus Torvalds
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[PATCH] ufs: write to hole in big file 



On UFS, this scenario:
	open(O_TRUNC)
	lseek(1024 * 1024 * 80)
	write("A")
	lseek(1024 * 2)
	write("A")

may cause access to invalid address.

This happened because of "goal" is calculated in wrong way in block
allocation path, as I see this problem exists also in 2.4.

We use construction like this i_data[lastfrag], i_data array of pointers to
direct blocks, indirect and so on, it has ceratain size ~20 elements, and
lastfrag may have value for example 40000.

Also this patch fixes related to handling such scenario issues, wrong
zeroing metadata, in case of block(not fragment) allocation, and wrong goal
calculation, when we allocate block

Signed-off-by: default avatarEvgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 08fb306f

fs/ufs/inode.c

+21 −14
Original line number Diff line number Diff line
@@ -169,18 +169,20 @@ static void ufs_clear_frag(struct inode *inode, struct buffer_head *bh) 


static struct buffer_head *

ufs_clear_frags(struct inode *inode, sector_t beg,

		unsigned int n)

		unsigned int n, sector_t want)

{

	struct buffer_head *res, *bh;

	struct buffer_head *res = NULL, *bh;

	sector_t end = beg + n;



	res = sb_getblk(inode->i_sb, beg);

	ufs_clear_frag(inode, res);

	for (++beg; beg < end; ++beg) {

	for (; beg < end; ++beg) {

		bh = sb_getblk(inode->i_sb, beg);

		ufs_clear_frag(inode, bh);

		if (want != beg)

			brelse(bh);

		else

			res = bh;

	}

	BUG_ON(!res);

	return res;

}
@@ -265,7 +267,9 @@ repeat: 
			lastfrag = ufsi->i_lastfrag;

			

		}

		goal = fs32_to_cpu(sb, ufsi->i_u1.i_data[lastblock]) + uspi->s_fpb;

		tmp = fs32_to_cpu(sb, ufsi->i_u1.i_data[lastblock]);

		if (tmp)

			goal = tmp + uspi->s_fpb;

		tmp = ufs_new_fragments (inode, p, fragment - blockoff, 

					 goal, required + blockoff,

					 err, locked_page);
@@ -277,13 +281,15 @@ repeat: 
		tmp = ufs_new_fragments(inode, p, fragment - (blockoff - lastblockoff),

					fs32_to_cpu(sb, *p), required +  (blockoff - lastblockoff),

					err, locked_page);

	}

	} else /* (lastblock > block) */ {

	/*

	 * We will allocate new block before last allocated block

	 */

	else /* (lastblock > block) */ {

		if (lastblock && (tmp = fs32_to_cpu(sb, ufsi->i_u1.i_data[lastblock-1])))

		if (block) {

			tmp = fs32_to_cpu(sb, ufsi->i_u1.i_data[block-1]);

			if (tmp)

				goal = tmp + uspi->s_fpb;

		}

		tmp = ufs_new_fragments(inode, p, fragment - blockoff,

					goal, uspi->s_fpb, err, locked_page);

	}
@@ -296,7 +302,7 @@ repeat: 
	}



	if (!phys) {

		result = ufs_clear_frags(inode, tmp + blockoff, required);

		result = ufs_clear_frags(inode, tmp, required, tmp + blockoff);

	} else {

		*phys = tmp + blockoff;

		result = NULL;
@@ -383,7 +389,7 @@ repeat: 
		}

	}



	if (block && (tmp = fs32_to_cpu(sb, ((__fs32*)bh->b_data)[block-1]) + uspi->s_fpb))

	if (block && (tmp = fs32_to_cpu(sb, ((__fs32*)bh->b_data)[block-1])))

		goal = tmp + uspi->s_fpb;

	else

		goal = bh->b_blocknr + uspi->s_fpb;
@@ -397,7 +403,8 @@ repeat: 




	if (!phys) {

		result = ufs_clear_frags(inode, tmp + blockoff, uspi->s_fpb);

		result = ufs_clear_frags(inode, tmp, uspi->s_fpb,

					 tmp + blockoff);

	} else {

		*phys = tmp + blockoff;

		*new = 1;

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