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| author | Al Viro <viro@zeniv.linux.org.uk> | 2016-08-17 16:36:37 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-09-24 10:09:40 +0200 |
| commit | 5ed23652be92fbf1c033bb65428b941b96c365ab (patch) | |
| tree | 204c5f8e7901cb522b3cbe4fec205ee5220465bc /include | |
| parent | b05faef93808bf2f28cc855e40b82af2368a7df6 (diff) | |
| download | lwn-5ed23652be92fbf1c033bb65428b941b96c365ab.tar.gz lwn-5ed23652be92fbf1c033bb65428b941b96c365ab.zip | |
asm-generic: make copy_from_user() zero the destination properly
commit 2545e5da080b4839dd859e3b09343a884f6ab0e3 upstream.
... 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.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/asm-generic/uaccess.h | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h index c0019f76ee34..32901d11f8c4 100644 --- a/include/asm-generic/uaccess.h +++ b/include/asm-generic/uaccess.h @@ -261,11 +261,13 @@ 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, |