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authorAl Viro <viro@zeniv.linux.org.uk>2016-08-17 23:36:37 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2016-09-10 02:34:32 +0300
commit2545e5da080b4839dd859e3b09343a884f6ab0e3 (patch)
treeaebbe4cb83704b6a7c09b590adc3e1dd84fc139d /include
parent2561d309dfd1555e781484af757ed0115035ddb3 (diff)
downloadlinux-2545e5da080b4839dd859e3b09343a884f6ab0e3.tar.xz
asm-generic: make copy_from_user() zero the destination properly
... in all cases, including the failing access_ok() Note that some architectures using asm-generic/uaccess.h have __copy_from_user() not zeroing the tail on failure halfway through. This variant works either way. Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'include')
-rw-r--r--include/asm-generic/uaccess.h10
1 files changed, 6 insertions, 4 deletions
diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
index 1bfa602958f2..04e21a41796a 100644
--- a/include/asm-generic/uaccess.h
+++ b/include/asm-generic/uaccess.h
@@ -257,11 +257,13 @@ extern int __get_user_bad(void) __attribute__((noreturn));
static inline long copy_from_user(void *to,
const void __user * from, unsigned long n)
{
+ unsigned long res = n;
might_fault();
- if (access_ok(VERIFY_READ, from, n))
- return __copy_from_user(to, from, n);
- else
- return n;
+ if (likely(access_ok(VERIFY_READ, from, n)))
+ res = __copy_from_user(to, from, n);
+ if (unlikely(res))
+ memset(to + (n - res), 0, res);
+ return res;
}
static inline long copy_to_user(void __user *to,