xtensa: fix {get,put}_user() for 64bit values (6595d144) · Commits · 戴 / test

First of all, on short copies __copy_{to,from}_user() return the amount of bytes left uncopied, *not* -EFAULT. get_user() and put_user() are expected to return -EFAULT on failure. Another problem is get_user(v32, (__u64 __user *)p); that should fetch 64bit value and the assign it to v32, truncating it in process. Current code, OTOH, reads 8 bytes of data and stores them at the address of v32, stomping on the 4 bytes that follow v32 itself. Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk> Signed-off-by:

Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/include/asm/uaccess.h

+11 −2

Original line number	Diff line number	Diff line
		@@ -100,7 +100,7 @@ do { \
		case 4: __put_user_asm(x, ptr, retval, 4, "s32i", __cb); break; \
		case 8: { \
		__typeof__(*ptr) __v64 = x; \
		retval = __copy_to_user(ptr, &__v64, 8); \
		retval = __copy_to_user(ptr, &__v64, 8) ? -EFAULT : 0; \
		break; \
		} \
		default: __put_user_bad(); \
		@@ -198,7 +198,16 @@ do { \
		case 1: __get_user_asm(x, ptr, retval, 1, "l8ui", __cb); break;\
		case 2: __get_user_asm(x, ptr, retval, 2, "l16ui", __cb); break;\
		case 4: __get_user_asm(x, ptr, retval, 4, "l32i", __cb); break;\
		case 8: retval = __copy_from_user(&x, ptr, 8); break; \
		case 8: { \
		u64 __x; \
		if (unlikely(__copy_from_user(&__x, ptr, 8))) { \
		retval = -EFAULT; \
		(x) = 0; \
		} else { \
		(x) = *(__force __typeof__((ptr)))&__x; \
		} \
		break; \
		} \
		default: (x) = __get_user_bad(); \
		} \
		} while (0)

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