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Commit 19791a7c authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon
Browse files

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>
parent ad40bdaf

arch/arm64/kernel/ptrace.c

+10 −4
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <linux/sched/signal.h>

#include <linux/sched/task_stack.h>

#include <linux/mm.h>

#include <linux/nospec.h>

#include <linux/smp.h>

#include <linux/ptrace.h>

#include <linux/user.h>
@@ -249,15 +250,20 @@ 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)

		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)

		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;

}