Commit b307f99d authored Sep 04, 2019 by Greg Kroah-Hartman

x86/ptrace: fix up botched merge of spectrev1 fix

I incorrectly merged commit 31a2fbb390fe ("x86/ptrace: Fix possible
spectre-v1 in ptrace_get_debugreg()") when backporting it, as was
graciously pointed out at
https://grsecurity.net/teardown_of_a_failed_linux_lts_spectre_fix.php



Resolve the upstream difference with the stable kernel merge to properly
protect things.

Reported-by: Brad Spengler <spender@grsecurity.net>
Cc: Dianzhang Chen <dianzhangchen0@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <bp@alien8.de>
Cc: <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 3b26fa9e

arch/x86/kernel/ptrace.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -652,11 +652,10 @@ static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n)
		{
		struct thread_struct *thread = &tsk->thread;
		unsigned long val = 0;
		int index = n;

		if (n < HBP_NUM) {
		int index = array_index_nospec(n, HBP_NUM);
		struct perf_event *bp = thread->ptrace_bps[index];
		index = array_index_nospec(index, HBP_NUM);

		if (bp)
		val = bp->hw.info.address;