From: Eugene Syromiatnikov <esyr@redhat.com>
Date: Wed, 15 Jan 2020 16:35:38 +0000 (+0100)
Subject: io_uring: fix compat for IORING_REGISTER_FILES_UPDATE
X-Git-Tag: baikal/mips/sdk5.9~14528^2
X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=1c1c29b3ba535f37d30041f3db1f541a2e51eabe;p=kernel.git

io_uring: fix compat for IORING_REGISTER_FILES_UPDATE

fds field of struct io_uring_files_update is problematic with regards
to compat user space, as pointer size is different in 32-bit, 32-on-64-bit,
and 64-bit user space.  In order to avoid custom handling of compat in
the syscall implementation, make fds __u64 and use u64_to_user_ptr in
order to retrieve it.  Also, align the field naturally and check that
no garbage is passed there.

Fixes: 9c9f2a4231568d8b ("io_uring: add support for IORING_REGISTER_FILES_UPDATE")
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 187dd94fd6b12..5953d7f136901 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4463,13 +4463,15 @@ static int io_sqe_files_update(struct io_ring_ctx *ctx, void __user *arg,
 		return -EINVAL;
 	if (copy_from_user(&up, arg, sizeof(up)))
 		return -EFAULT;
+	if (up.resv)
+		return -EINVAL;
 	if (check_add_overflow(up.offset, nr_args, &done))
 		return -EOVERFLOW;
 	if (done > ctx->nr_user_files)
 		return -EINVAL;
 
 	done = 0;
-	fds = (__s32 __user *) up.fds;
+	fds = u64_to_user_ptr(up.fds);
 	while (nr_args) {
 		struct fixed_file_table *table;
 		unsigned index;
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index a3300e1b9a010..55cfcb71606db 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -178,7 +178,8 @@ struct io_uring_params {
 
 struct io_uring_files_update {
 	__u32 offset;
-	__s32 *fds;
+	__u32 resv;
+	__aligned_u64 /* __s32 * */ fds;
 };
 
 #endif