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[PATCH] uml: hostfs - fix possible PAGE_CACHE_SHIFT overflows

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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: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Paolo 'Blaisorblade' Giarrusso 2005-12-29 17:39:57 +01:00 • committed by Linus Torvalds
parent 3d0a07e331
commit 30f04a4efa
1 changed files with 6 additions and 1 deletions
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7
fs/hostfs/hostfs_kern.c
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@ -501,11 +501,16 @@ int hostfs_commit_write(struct file *file, struct page *page, unsigned from,
long long start;
int err = 0;
start = (long long) (page->index << PAGE_CACHE_SHIFT) + from;
start = (((long long) page->index) << PAGE_CACHE_SHIFT) + from;
buffer = kmap(page);
err = write_file(FILE_HOSTFS_I(file)->fd, &start, buffer + from,
to - from);
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))
inode->i_size = start;