ARM: 8797/1: spectre-v1.1: harden __copy_to_user

Julien Thierry · Russell King · commit a1d09e074250 · 2018-10-05T10:51:15.000+01:00
Sanitize user pointer given to __copy_to_user, both for standard version
and memcopy version of the user accessor.

Signed-off-by: Julien Thierry &lt;julien.thierry@arm.com&gt;
Signed-off-by: Russell King &lt;rmk+kernel@armlinux.org.uk&gt;
diff --git a/arch/arm/lib/copy_to_user.S b/arch/arm/lib/copy_to_user.S
@@ -94,6 +94,11 @@
 
 ENTRY(__copy_to_user_std)
 WEAK(arm_copy_to_user)
+#ifdef CONFIG_CPU_SPECTRE
+	get_thread_info r3
+	ldr	r3, [r3, #TI_ADDR_LIMIT]
+	uaccess_mask_range_ptr r0, r2, r3, ip
+#endif
 
 #include "copy_template.S"
 
@@ -108,4 +113,3 @@ ENDPROC(__copy_to_user_std)
 	rsb	r0, r0, r2
 	copy_abort_end
 	.popsection
-
diff --git a/arch/arm/lib/uaccess_with_memcpy.c b/arch/arm/lib/uaccess_with_memcpy.c
@@ -152,7 +152,8 @@ arm_copy_to_user(void __user *to, const void *from, unsigned long n)
 		n = __copy_to_user_std(to, from, n);
 		uaccess_restore(ua_flags);
 	} else {
-		n = __copy_to_user_memcpy(to, from, n);
+		n = __copy_to_user_memcpy(uaccess_mask_range_ptr(to, n),
+					  from, n);
 	}
 	return n;
 }

Original file line number	Diff line number	Diff line change
`@@ -152,7 +152,8 @@ arm_copy_to_user(void __user to, const void from, unsigned long n)`
`152`	`152`	`n = __copy_to_user_std(to, from, n);`
`153`	`153`	`uaccess_restore(ua_flags);`
`154`	`154`	`} else {`
`155`		`- n = __copy_to_user_memcpy(to, from, n);`
	`155`	`+ n = __copy_to_user_memcpy(uaccess_mask_range_ptr(to, n),`
	`156`	`+ from, n);`
`156`	`157`	`}`
`157`	`158`	`return n;`
`158`	`159`	`}`