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| author | Al Viro <viro@zeniv.linux.org.uk> | 2016-08-17 23:36:37 +0300 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2016-11-20 04:01:37 +0300 |
| commit | 263fd98a0f2c8bb934ac2a25d97f9913378a4803 (patch) | |
| tree | 00e143cfa3510dded32ad044d08bcb1be9eccb79 | |
| parent | 536e7d5ea02825c12e64356149a1f4c6691efd7b (diff) | |
| download | linux-263fd98a0f2c8bb934ac2a25d97f9913378a4803.tar.xz | |
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>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -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 ac68c999b6c2..61dada277520 100644 --- a/include/asm-generic/uaccess.h +++ b/include/asm-generic/uaccess.h @@ -243,11 +243,13 @@ 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_sleep(); - 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, |