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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>
zero-colors
Al Viro 2017-06-29 21:52:57 -04:00
parent aa28de275a
commit 72e809ed81
1 changed files with 17 additions and 0 deletions
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17
lib/iov_iter.c
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@ -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);