bio: take care not overflow page count when mapping/copying user data
If the iovec is being set up in a way that causes uaddr + PAGE_SIZE
to overflow, we could end up attempting to map a huge number of
pages. Check for this invalid input type.
Reported-by: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/fs/bio.c b/fs/bio.c
index 8317a2c..4bd454f 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -834,6 +834,12 @@
end = (uaddr + iov[i].iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
start = uaddr >> PAGE_SHIFT;
+ /*
+ * Overflow, abort
+ */
+ if (end < start)
+ return ERR_PTR(-EINVAL);
+
nr_pages += end - start;
len += iov[i].iov_len;
}
@@ -962,6 +968,12 @@
unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long start = uaddr >> PAGE_SHIFT;
+ /*
+ * Overflow, abort
+ */
+ if (end < start)
+ return ERR_PTR(-EINVAL);
+
nr_pages += end - start;
/*
* buffer must be aligned to at least hardsector size for now
@@ -989,7 +1001,7 @@
unsigned long start = uaddr >> PAGE_SHIFT;
const int local_nr_pages = end - start;
const int page_limit = cur_page + local_nr_pages;
-
+
ret = get_user_pages_fast(uaddr, local_nr_pages,
write_to_vm, &pages[cur_page]);
if (ret < local_nr_pages) {