From: Al Viro <viro@zeniv.linux.org.uk>
To: Max Filippov <jcmvbkbc@gmail.com>
Cc: linux-xtensa@linux-xtensa.org, linux-kernel@vger.kernel.org
Subject: [PATCH] xtensa: fix {get,put}_user() for 64bit values
Date: Wed, 9 Oct 2019 20:21:05 +0100 [thread overview]
Message-ID: <20191009192105.GC26530@ZenIV.linux.org.uk> (raw)
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>
--
diff --git a/arch/xtensa/include/asm/uaccess.h b/arch/xtensa/include/asm/uaccess.h
index 6792928ba84a..155174ddb7ae 100644
--- a/arch/xtensa/include/asm/uaccess.h
+++ b/arch/xtensa/include/asm/uaccess.h
@@ -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 +198,12 @@ 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 = 0; \
+ retval = __copy_from_user(&__x, ptr, 8) ? -EFAULT : 0; \
+ (x) = *(__force __typeof__(*(ptr)) *) &__x; \
+ break; \
+ } \
default: (x) = __get_user_bad(); \
} \
} while (0)
next reply other threads:[~2019-10-09 19:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-09 19:21 Al Viro [this message]
2019-10-10 1:38 ` [PATCH] xtensa: fix {get,put}_user() for 64bit values Max Filippov
2019-10-10 1:56 ` Al Viro
2019-10-10 2:11 ` Max Filippov
2019-10-10 14:29 ` Al Viro
2019-10-11 3:35 ` Max Filippov
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