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authorPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>2005-12-29 17:39:57 +0100
committerLinus Torvalds <torvalds@g5.osdl.org>2005-12-29 09:48:15 -0800
commit30f04a4efa73dc80bf3f59f3f19ad5a24ac5ac0a (patch)
tree0f7f165bcf73bf26f782a2b56d05020ea6d4d5b0
parent3d0a07e3310c947c048bd01d8d0efa0e4fae5ba9 (diff)
downloadlinux-linaro-stable-30f04a4efa73dc80bf3f59f3f19ad5a24ac5ac0a.tar.gz
[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: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--fs/hostfs/hostfs_kern.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
index 3aac164c7726..b3ad0bd0312f 100644
--- a/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@ -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;