media: v4l2-compat-ioctl32: simplify casts

Making the cast right for get_user/put_user is not trivial, as
it needs to ensure that the types are the correct ones.

Improve it by using macros.

Tested with vivid with:
	$ sudo modprobe vivid no_error_inj=1
	$ v4l2-compliance-32bits -a -s10 >32bits && v4l2-compliance-64bits -a -s10 > 64bits && diff -U0 32bits 64bits
	--- 32bits	2018-04-17 11:18:29.141240772 -0300
	+++ 64bits	2018-04-17 11:18:40.635282341 -0300
	@@ -1 +1 @@
	-v4l2-compliance SHA   : bc71e4a67c6fbc5940062843bc41e7c8679634ce, 32 bits
	+v4l2-compliance SHA   : bc71e4a67c6fbc5940062843bc41e7c8679634ce, 64 bits

Using the latest version of v4l-utils with this patch applied:
	https://patchwork.linuxtv.org/patch/48746/

Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
index 543dab6..a7ed123 100644 (file)
--- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
+++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
@@ -30,6 +30,24 @@
        get_user(__assign_tmp, from) || put_user(__assign_tmp, to);     \
 })
 
+#define get_user_cast(__x, __ptr)                                      \
+({                                                                     \
+       get_user(__x, (typeof(*__ptr) __user *)(__ptr));                \
+})
+
+#define put_user_force(__x, __ptr)                                     \
+({                                                                     \
+       put_user((typeof(*__x) __force *)(__x), __ptr);                 \
+})
+
+#define assign_in_user_cast(to, from)                                  \
+({                                                                     \
+       typeof(*from) __assign_tmp;                                     \
+                                                                       \
+       get_user_cast(__assign_tmp, from) || put_user(__assign_tmp, to);\
+})
+
+
 static long native_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
        long ret = -ENOIOCTLCMD;
@@ -543,8 +561,7 @@ static int get_v4l2_buffer32(struct v4l2_buffer __user *p64,
                        return -EFAULT;
 
                uplane = aux_buf;
-               if (put_user((__force struct v4l2_plane *)uplane,
-                            &p64->m.planes))
+               if (put_user_force(uplane, &p64->m.planes))
                        return -EFAULT;
 
                while (num_planes--) {
@@ -683,7 +700,7 @@ static int get_v4l2_framebuffer32(struct v4l2_framebuffer __user *p64,
 
        if (!access_ok(VERIFY_READ, p32, sizeof(*p32)) ||
            get_user(tmp, &p32->base) ||
-           put_user((void __force *)compat_ptr(tmp), &p64->base) ||
+           put_user_force(compat_ptr(tmp), &p64->base) ||
            assign_in_user(&p64->capability, &p32->capability) ||
            assign_in_user(&p64->flags, &p32->flags) ||
            copy_in_user(&p64->fmt, &p32->fmt, sizeof(p64->fmt)))
@@ -832,8 +849,7 @@ static int get_v4l2_ext_controls32(struct file *file,
        if (aux_space < count * sizeof(*kcontrols))
                return -EFAULT;
        kcontrols = aux_buf;
-       if (put_user((__force struct v4l2_ext_control *)kcontrols,
-                    &p64->controls))
+       if (put_user_force(kcontrols, &p64->controls))
                return -EFAULT;
 
        for (n = 0; n < count; n++) {
@@ -899,10 +915,9 @@ static int put_v4l2_ext_controls32(struct file *file,
                unsigned int size = sizeof(*ucontrols);
                u32 id;
 
-               if (get_user(id, (unsigned int __user *)&kcontrols->id) ||
+               if (get_user_cast(id, &kcontrols->id) ||
                    put_user(id, &ucontrols->id) ||
-                   assign_in_user(&ucontrols->size,
-                                  (unsigned int __user *)&kcontrols->size) ||
+                   assign_in_user_cast(&ucontrols->size, &kcontrols->size) ||
                    copy_in_user(&ucontrols->reserved2,
                                 (void __user *)&kcontrols->reserved2,
                                 sizeof(ucontrols->reserved2)))
@@ -971,10 +986,9 @@ static int get_v4l2_edid32(struct v4l2_edid __user *p64,
        if (!access_ok(VERIFY_READ, p32, sizeof(*p32)) ||
            assign_in_user(&p64->pad, &p32->pad) ||
            assign_in_user(&p64->start_block, &p32->start_block) ||
-           assign_in_user(&p64->blocks,
-                          (u32 __user *)&p32->blocks) ||
+           assign_in_user_cast(&p64->blocks, &p32->blocks) ||
            get_user(tmp, &p32->edid) ||
-           put_user((void __force *)compat_ptr(tmp), &p64->edid) ||
+           put_user_force(compat_ptr(tmp), &p64->edid) ||
            copy_in_user(p64->reserved, p32->reserved, sizeof(p64->reserved)))
                return -EFAULT;
        return 0;