Fix: kernel/ptrace.c: ptrace_peek_siginfo() missing __put_user() validation
This __put_user() could be used by unprivileged processes to write into
kernel memory. The issue here is that even if copy_siginfo_to_user()
fails, the error code is not checked before __put_user() is executed.
Luckily, ptrace_peek_siginfo() has been added within the 3.10-rc cycle,
so it has not hit a stable release yet.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index aed981a..335a7ae 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -665,20 +665,22 @@
if (unlikely(is_compat_task())) {
compat_siginfo_t __user *uinfo = compat_ptr(data);
- ret = copy_siginfo_to_user32(uinfo, &info);
- ret |= __put_user(info.si_code, &uinfo->si_code);
+ if (copy_siginfo_to_user32(uinfo, &info) ||
+ __put_user(info.si_code, &uinfo->si_code)) {
+ ret = -EFAULT;
+ break;
+ }
+
} else
#endif
{
siginfo_t __user *uinfo = (siginfo_t __user *) data;
- ret = copy_siginfo_to_user(uinfo, &info);
- ret |= __put_user(info.si_code, &uinfo->si_code);
- }
-
- if (ret) {
- ret = -EFAULT;
- break;
+ if (copy_siginfo_to_user(uinfo, &info) ||
+ __put_user(info.si_code, &uinfo->si_code)) {
+ ret = -EFAULT;
+ break;
+ }
}
data += sizeof(siginfo_t);
