[PATCH AUTOSEL 5.15 45/69] iov_iter_get_pages{,_alloc}(): cap the maxsize with MAX_RW_COUNT

[Sasha Levin <sashal@kernel.org>]

From: Al Viro <viro@zeniv.linux.org.uk>

[ Upstream commit 7392ed1734c319150b5ddec3f192a6405728e8d0 ]

All callers can and should handle iov_iter_get_pages() returning
fewer pages than requested.  All in-kernel ones do.  And it makes
the arithmetical overflow analysis much simpler...

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 lib/iov_iter.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 6cf2d66fb839..ce24835abe55 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1522,6 +1522,8 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
 		maxsize = i->count;
 	if (!maxsize)
 		return 0;
+	if (maxsize > MAX_RW_COUNT)
+		maxsize = MAX_RW_COUNT;
 
 	if (likely(iter_is_iovec(i))) {
 		unsigned int gup_flags = 0;
@@ -1642,6 +1644,8 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 		maxsize = i->count;
 	if (!maxsize)
 		return 0;
+	if (maxsize > MAX_RW_COUNT)
+		maxsize = MAX_RW_COUNT;
 
 	if (likely(iter_is_iovec(i))) {
 		unsigned int gup_flags = 0;
-- 
2.35.1