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Commit 30f04a4e authored by Paolo 'Blaisorblade' Giarrusso's avatar Paolo 'Blaisorblade' Giarrusso Committed by Linus Torvalds
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[PATCH] uml: hostfs - fix possible PAGE_CACHE_SHIFT overflows 



Prevent page->index << PAGE_CACHE_SHIFT from overflowing.

There is a casting there, but was added without care, so it's at the wrong
place. Note the extra parens around the shift - "+" is higher precedence than
"<<", leading to a GCC warning which saved all us.

Signed-off-by: default avatarPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 3d0a07e3

fs/hostfs/hostfs_kern.c

+6 −1
Original line number Original line Diff line number Diff line
@@ -501,11 +501,16 @@ int hostfs_commit_write(struct file *file, struct page *page, unsigned from, 
	long long start;

	long long start;

	int err = 0;

	int err = 0;





	start = (long long) (page->index << PAGE_CACHE_SHIFT) + from;

	start = (((long long) page->index) << PAGE_CACHE_SHIFT) + from;

	buffer = kmap(page);

	buffer = kmap(page);

	err = write_file(FILE_HOSTFS_I(file)->fd, &start, buffer + from,

	err = write_file(FILE_HOSTFS_I(file)->fd, &start, buffer + from,

			 to - from);

			 to - from);

	if(err > 0) err = 0;

	if(err > 0) err = 0;



	/* Actually, if !err, write_file has added to-from to start, so, despite

	 * the appearance, we are comparing i_size against the _last_ written

	 * location, as we should. */



	if(!err && (start > inode->i_size))

	if(!err && (start > inode->i_size))

		inode->i_size = start;

		inode->i_size = start;