From: Omar Sandoval <osandov@xxxxxx>
The recent conversion to inline functions made two mistakes:
1. It tries to copy the full amount requested (bytes), not just what's
available in the kmap'd page (n).
2. It's not applying the offset in the first page.
Note that copy_page_to_iter_nofault() is only used by /proc/kcore. This
was detected by drgn's test suite.
Fixes: f1982740f5e7 ("iov_iter: Convert iterate*() to inline funcs")
Signed-off-by: Omar Sandoval <osandov@xxxxxx>
---
lib/iov_iter.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index de7d11cf4c63..8ff6824a1005 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -409,7 +409,7 @@ size_t copy_page_to_iter_nofault(struct page *page, unsigned offset, size_t byte
void *kaddr = kmap_local_page(page);
size_t n = min(bytes, (size_t)PAGE_SIZE - offset);
- n = iterate_and_advance(i, bytes, kaddr,
+ n = iterate_and_advance(i, n, kaddr + offset,
copy_to_user_iter_nofault,
memcpy_to_iter);
kunmap_local(kaddr);
--
2.42.0
