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authorGreg Ungerer <gerg@linux-m68k.org>2020-01-17 16:28:19 +1000
committerGreg Ungerer <gerg@linux-m68k.org>2020-02-03 14:43:35 +1000
commit8044aad70a1fbd66376cdb2a13e536db9dd6c132 (patch)
tree193e4c1f48150567f7c32884a812a2bdb17b3f94 /arch
parentd5fae240b9bdb2d374624e6aa9f99a4527f111ec (diff)
m68knommu: fix memcpy() out of bounds warning in get_user()
Newer versions of gcc are giving warnings in the non-MMU m68k version of the get_user() macro: ./arch/m68k/include/asm/string.h:72:25: warning: ‘__builtin_memcpy’ forming offset [3, 4] is out of the bounds [0, 2] of object ‘__gu_val’ with type ‘short unsigned int’ [-Warray-bounds] The warnings are generated when smaller sized variables are used as the result of user space pointers to larger values. For example a short/2-byte variable stores the result of a user space int (4-byte) pointer. The warning is in the 8-byte branch of get_user() - even though that branch is not the taken branch in the warning cases. Refactor the 8-byte branch of get_user() so that it uses a correctly formed union type to read and write the source and destination objects. Keep using the memcpy() just in case the user space pointer is not naturaly aligned (not required for ColdFire, but needed for early 68000). Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/m68k/include/asm/uaccess_no.h19
1 files changed, 11 insertions, 8 deletions
diff --git a/arch/m68k/include/asm/uaccess_no.h b/arch/m68k/include/asm/uaccess_no.h
index 0134008bf539..6bc80c35726d 100644
--- a/arch/m68k/include/asm/uaccess_no.h
+++ b/arch/m68k/include/asm/uaccess_no.h
@@ -71,26 +71,29 @@ extern int __put_user_bad(void);
#define get_user(x, ptr) \
({ \
int __gu_err = 0; \
- typeof(x) __gu_val = 0; \
switch (sizeof(*(ptr))) { \
case 1: \
- __get_user_asm(__gu_err, __gu_val, ptr, b, "=d"); \
+ __get_user_asm(__gu_err, x, ptr, b, "=d"); \
break; \
case 2: \
- __get_user_asm(__gu_err, __gu_val, ptr, w, "=r"); \
+ __get_user_asm(__gu_err, x, ptr, w, "=r"); \
break; \
case 4: \
- __get_user_asm(__gu_err, __gu_val, ptr, l, "=r"); \
+ __get_user_asm(__gu_err, x, ptr, l, "=r"); \
break; \
- case 8: \
- memcpy((void *) &__gu_val, ptr, sizeof (*(ptr))); \
+ case 8: { \
+ union { \
+ u64 l; \
+ __typeof__(*(ptr)) t; \
+ } __gu_val; \
+ memcpy(&__gu_val.l, ptr, sizeof(__gu_val.l)); \
+ (x) = __gu_val.t; \
break; \
+ } \
default: \
- __gu_val = 0; \
__gu_err = __get_user_bad(); \
break; \
} \
- (x) = (typeof(*(ptr))) __gu_val; \
__gu_err; \
})
#define __get_user(x, ptr) get_user(x, ptr)