tree d5b5f0604c0cd3ea41bdcf5c1eda8793bc720129
parent 94d7dbf108813ea45a91e27e9a8bd231d5a23fa7
author Jann Horn <jannh@google.com> 1525997941 +0200
committer Linus Torvalds <torvalds@linux-foundation.org> 1525999918 -0700

compat: fix 4-byte infoleak via uninitialized struct field

Commit 3a4d44b61625 ("ntp: Move adjtimex related compat syscalls to
native counterparts") removed the memset() in compat_get_timex().  Since
then, the compat adjtimex syscall can invoke do_adjtimex() with an
uninitialized ->tai.

If do_adjtimex() doesn't write to ->tai (e.g.  because the arguments are
invalid), compat_put_timex() then copies the uninitialized ->tai field
to userspace.

Fix it by adding the memset() back.

Fixes: 3a4d44b61625 ("ntp: Move adjtimex related compat syscalls to native counterparts")
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>