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Commit 14d6e289 authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon
Browse files

arm64: fix possible spectre-v1 write in ptrace_hbp_set_event() 



It's possible for userspace to control idx. Sanitize idx when using it
as an array index, to inhibit the potential spectre-v1 write gadget.

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 11527b3e

arch/arm64/kernel/ptrace.c

+11 −8
Original line number Original line Diff line number Diff line
@@ -277,19 +277,22 @@ static int ptrace_hbp_set_event(unsigned int note_type, 




	switch (note_type) {

	switch (note_type) {

	case NT_ARM_HW_BREAK:

	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);

		tsk->thread.debug.hbp_break[idx] = bp;

		tsk->thread.debug.hbp_break[idx] = bp;

		err = 0;

		err = 0;

		}

		break;

		break;

	case NT_ARM_HW_WATCH:

	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);

		tsk->thread.debug.hbp_watch[idx] = bp;

		tsk->thread.debug.hbp_watch[idx] = bp;

		err = 0;

		err = 0;

		}

		break;

		break;

	}

	}





out:

	return err;

	return err;

}

}