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authorAl Viro <viro@zeniv.linux.org.uk>2017-06-29 21:52:57 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2017-06-29 22:21:23 -0400
commit72e809ed81edf81b93d3a36b7238ba50d67f043d (patch)
tree77da2a68e94ab270adfde753e1fd00ac4bfe1a18
parentaa28de275a248879f9828cb9f7ee7e119c72ff96 (diff)
downloadlinux-72e809ed81edf81b93d3a36b7238ba50d67f043d.tar.bz2
iov_iter: sanity checks for copy to/from page primitives
for now - just that we don't attempt to cross out of compound page Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--lib/iov_iter.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index bc4a63ebe91a..b50a478f9d34 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -639,9 +639,20 @@ bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
}
EXPORT_SYMBOL(_copy_from_iter_full_nocache);
+static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
+{
+ size_t v = n + offset;
+ if (likely(n <= v && v <= (PAGE_SIZE << compound_order(page))))
+ return true;
+ WARN_ON(1);
+ return false;
+}
+
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
+ if (unlikely(!page_copy_sane(page, offset, bytes)))
+ return 0;
if (i->type & (ITER_BVEC|ITER_KVEC)) {
void *kaddr = kmap_atomic(page);
size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
@@ -657,6 +668,8 @@ EXPORT_SYMBOL(copy_page_to_iter);
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
+ if (unlikely(!page_copy_sane(page, offset, bytes)))
+ return 0;
if (unlikely(i->type & ITER_PIPE)) {
WARN_ON(1);
return 0;
@@ -713,6 +726,10 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
struct iov_iter *i, unsigned long offset, size_t bytes)
{
char *kaddr = kmap_atomic(page), *p = kaddr + offset;
+ if (unlikely(!page_copy_sane(page, offset, bytes))) {
+ kunmap_atomic(kaddr);
+ return 0;
+ }
if (unlikely(i->type & ITER_PIPE)) {
kunmap_atomic(kaddr);
WARN_ON(1);