Commit 12ef5692 authored by Mark Rutland's avatar Mark Rutland Committed by Kleber Sacilotto de Souza

arm64: fix possible spectre-v1 in ptrace_hbp_get_event()

It's possible for userspace to control idx. Sanitize idx when using it
as an array index.

Found by smatch.
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>

CVE-2017-5753

(cherry picked from commit 19791a7c)
Signed-off-by: default avatarJuerg Haefliger <juergh@canonical.com>
Acked-by: default avatarStefan Bader <stefan.bader@canonical.com>
Acked-by: default avatarKleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: default avatarKleber Sacilotto de Souza <kleber.souza@canonical.com>
parent eb4a3a43
......@@ -24,6 +24,7 @@
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/nospec.h>
#include <linux/smp.h>
#include <linux/ptrace.h>
#include <linux/user.h>
......@@ -145,15 +146,20 @@ static struct perf_event *ptrace_hbp_get_event(unsigned int note_type,
switch (note_type) {
case NT_ARM_HW_BREAK:
if (idx < ARM_MAX_BRP)
bp = tsk->thread.debug.hbp_break[idx];
if (idx >= ARM_MAX_BRP)
goto out;
idx = array_index_nospec(idx, ARM_MAX_BRP);
bp = tsk->thread.debug.hbp_break[idx];
break;
case NT_ARM_HW_WATCH:
if (idx < ARM_MAX_WRP)
bp = tsk->thread.debug.hbp_watch[idx];
if (idx >= ARM_MAX_WRP)
goto out;
idx = array_index_nospec(idx, ARM_MAX_WRP);
bp = tsk->thread.debug.hbp_watch[idx];
break;
}
out:
return bp;
}
......
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