arm64: uaccess: Fix omissions from usercopy whitelist

[linux-2.6-microblaze.git] / arch / arm64 / include / asm / processor.h

diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 63d3850..7675989 100644 (file)
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -34,6 +34,8 @@
 
 #ifdef __KERNEL__
 
+#include <linux/build_bug.h>
+#include <linux/stddef.h>
 #include <linux/string.h>
 
 #include <asm/alternative.h>
@@ -103,11 +105,18 @@ struct cpu_context {
 
 struct thread_struct {
        struct cpu_context      cpu_context;    /* cpu context */
-       unsigned long           tp_value;       /* TLS register */
-#ifdef CONFIG_COMPAT
-       unsigned long           tp2_value;
-#endif
-       struct user_fpsimd_state fpsimd_state;
+
+       /*
+        * Whitelisted fields for hardened usercopy:
+        * Maintainers must ensure manually that this contains no
+        * implicit padding.
+        */
+       struct {
+               unsigned long   tp_value;       /* TLS register */
+               unsigned long   tp2_value;
+               struct user_fpsimd_state fpsimd_state;
+       } uw;
+
        unsigned int            fpsimd_cpu;
        void                    *sve_state;     /* SVE registers, if any */
        unsigned int            sve_vl;         /* SVE vector length */
@@ -117,14 +126,17 @@ struct thread_struct {
        struct debug_info       debug;          /* debugging */
 };
 
-/*
- * Everything usercopied to/from thread_struct is statically-sized, so
- * no hardened usercopy whitelist is needed.
- */
 static inline void arch_thread_struct_whitelist(unsigned long *offset,
                                                unsigned long *size)
 {
-       *offset = *size = 0;
+       /* Verify that there is no padding among the whitelisted fields: */
+       BUILD_BUG_ON(sizeof_field(struct thread_struct, uw) !=
+                    sizeof_field(struct thread_struct, uw.tp_value) +
+                    sizeof_field(struct thread_struct, uw.tp2_value) +
+                    sizeof_field(struct thread_struct, uw.fpsimd_state));
+
+       *offset = offsetof(struct thread_struct, uw);
+       *size = sizeof_field(struct thread_struct, uw);
 }
 
 #ifdef CONFIG_COMPAT
@@ -132,13 +144,13 @@ static inline void arch_thread_struct_whitelist(unsigned long *offset,
 ({                                                                     \
        unsigned long *__tls;                                           \
        if (is_compat_thread(task_thread_info(t)))                      \
-               __tls = &(t)->thread.tp2_value;                         \
+               __tls = &(t)->thread.uw.tp2_value;                      \
        else                                                            \
-               __tls = &(t)->thread.tp_value;                          \
+               __tls = &(t)->thread.uw.tp_value;                       \
        __tls;                                                          \
  })
 #else
-#define task_user_tls(t)       (&(t)->thread.tp_value)
+#define task_user_tls(t)       (&(t)->thread.uw.tp_value)
 #endif
 
 /* Sync TPIDR_EL0 back to thread_struct for current */