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Fix: kernel/ptrace.c: ptrace_peek_siginfo() missing __put_user() validation

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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>
This commit is contained in:
Mathieu Desnoyers 2013-06-28 09:49:46 -04:00 committed by Linus Torvalds
parent bd2931b5cf
commit 706b23bde2
1 changed files with 11 additions and 9 deletions
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16
kernel/ptrace.c
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@ -665,21 +665,23 @@ static int ptrace_peek_siginfo(struct task_struct *child,
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) {
if (copy_siginfo_to_user(uinfo, &info) ||
__put_user(info.si_code, &uinfo->si_code)) {
ret = -EFAULT;
break;
}
}
data += sizeof(siginfo_t);
i++;