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>
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@ -665,20 +665,22 @@ static int ptrace_peek_siginfo(struct task_struct *child,
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if (unlikely(is_compat_task())) {
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compat_siginfo_t __user *uinfo = compat_ptr(data);
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ret = copy_siginfo_to_user32(uinfo, &info);
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ret |= __put_user(info.si_code, &uinfo->si_code);
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if (copy_siginfo_to_user32(uinfo, &info) ||
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__put_user(info.si_code, &uinfo->si_code)) {
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ret = -EFAULT;
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break;
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}
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} else
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#endif
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{
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siginfo_t __user *uinfo = (siginfo_t __user *) data;
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ret = copy_siginfo_to_user(uinfo, &info);
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ret |= __put_user(info.si_code, &uinfo->si_code);
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}
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if (ret) {
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ret = -EFAULT;
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break;
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if (copy_siginfo_to_user(uinfo, &info) ||
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__put_user(info.si_code, &uinfo->si_code)) {
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ret = -EFAULT;
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break;
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}
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}
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data += sizeof(siginfo_t);
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