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| author | Al Viro <viro@zeniv.linux.org.uk> | 2016-08-17 16:36:37 -0400 |
|---|---|---|
| committer | Sasha Levin <alexander.levin@verizon.com> | 2016-10-02 20:32:37 -0400 |
| commit | 08ac15d0e46bddb8dc9ae9bd939e844d7c2451b9 (patch) | |
| tree | 151231c70705082f885fc435273edba6d417a58b | |
| parent | ca79a8dbf9345058f26305c263dd871ae8d80dfe (diff) | |
| download | lwn-08ac15d0e46bddb8dc9ae9bd939e844d7c2451b9.tar.gz lwn-08ac15d0e46bddb8dc9ae9bd939e844d7c2451b9.zip | |
asm-generic: make copy_from_user() zero the destination properly
[ Upstream commit 2545e5da080b4839dd859e3b09343a884f6ab0e3 ]
... 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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
| -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 72d8803832ff..e8e50f69e3c6 100644 --- a/include/asm-generic/uaccess.h +++ b/include/asm-generic/uaccess.h @@ -255,11 +255,13 @@ 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, |