[PATCH] fix for generic_file_write iov problem
Here is the fix for the problem described in
http://bugzilla.kernel.org/show_bug.cgi?id=4721
Basically, problem is generic_file_buffered_write() is accessing beyond end
of the iov[] vector after handling the last vector. If we happen to cross
page boundary, we get a fault.
I think this simple patch is good enough. If we really don't want to
depend on the "count", then we need pass nr_segs to
filemap_set_next_iovec() and decrement it and check it.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/filemap.c b/mm/filemap.c
index b573607..c11418d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1954,7 +1954,9 @@
if (unlikely(nr_segs > 1)) {
filemap_set_next_iovec(&cur_iov,
&iov_base, status);
- buf = cur_iov->iov_base + iov_base;
+ if (count)
+ buf = cur_iov->iov_base +
+ iov_base;
} else {
iov_base += status;
}