From: Greg Kroah-Hartman <[email protected]> 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 <[email protected]> Cc: Dianzhang Chen <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: <[email protected]> Cc: <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/kernel/ptrace.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -652,11 +652,10 @@ static unsigned long ptrace_get_debugreg { 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;
