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-rw-r--r--lib/iov_iter.c61
1 files changed, 61 insertions, 0 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index fdae394172fa..7e43cd54c84c 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -573,6 +573,67 @@ size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
}
EXPORT_SYMBOL(_copy_to_iter);
+#ifdef CONFIG_ARCH_HAS_UACCESS_MCSAFE
+static int copyout_mcsafe(void __user *to, const void *from, size_t n)
+{
+ if (access_ok(VERIFY_WRITE, to, n)) {
+ kasan_check_read(from, n);
+ n = copy_to_user_mcsafe((__force void *) to, from, n);
+ }
+ return n;
+}
+
+static unsigned long memcpy_mcsafe_to_page(struct page *page, size_t offset,
+ const char *from, size_t len)
+{
+ unsigned long ret;
+ char *to;
+
+ to = kmap_atomic(page);
+ ret = memcpy_mcsafe(to + offset, from, len);
+ kunmap_atomic(to);
+
+ return ret;
+}
+
+size_t _copy_to_iter_mcsafe(const void *addr, size_t bytes, struct iov_iter *i)
+{
+ const char *from = addr;
+ unsigned long rem, curr_addr, s_addr = (unsigned long) addr;
+
+ if (unlikely(i->type & ITER_PIPE)) {
+ WARN_ON(1);
+ return 0;
+ }
+ if (iter_is_iovec(i))
+ might_fault();
+ iterate_and_advance(i, bytes, v,
+ copyout_mcsafe(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
+ ({
+ rem = memcpy_mcsafe_to_page(v.bv_page, v.bv_offset,
+ (from += v.bv_len) - v.bv_len, v.bv_len);
+ if (rem) {
+ curr_addr = (unsigned long) from;
+ bytes = curr_addr - s_addr - rem;
+ return bytes;
+ }
+ }),
+ ({
+ rem = memcpy_mcsafe(v.iov_base, (from += v.iov_len) - v.iov_len,
+ v.iov_len);
+ if (rem) {
+ curr_addr = (unsigned long) from;
+ bytes = curr_addr - s_addr - rem;
+ return bytes;
+ }
+ })
+ )
+
+ return bytes;
+}
+EXPORT_SYMBOL_GPL(_copy_to_iter_mcsafe);
+#endif /* CONFIG_ARCH_HAS_UACCESS_MCSAFE */
+
size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
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