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From: Will Deacon <will@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
	Luis Machado <luis.machado@linaro.org>,
	Kees Cook <keescook@chromium.org>, Will Deacon <will@kernel.org>,
	catalin.marinas@arm.com, Keno Fischer <keno@juliacomputing.com>,
	kernel-team@android.com
Subject: [PATCH v3 6/7] arm64: ptrace: Use NO_SYSCALL instead of -1 in syscall_trace_enter()
Date: Fri, 10 Jul 2020 14:07:01 +0100	[thread overview]
Message-ID: <20200710130702.30658-7-will@kernel.org> (raw)
In-Reply-To: <20200710130702.30658-1-will@kernel.org>

Setting a system call number of -1 is special, as it indicates that the
current system call should be skipped.

Use NO_SYSCALL instead of -1 when checking for this scenario, which is
different from the -1 returned due to a seccomp failure.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Keno Fischer <keno@juliacomputing.com>
Cc: Luis Machado <luis.machado@linaro.org>
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kernel/ptrace.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 89fbee3991a2..1e02e98e68dd 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -1856,12 +1856,12 @@ int syscall_trace_enter(struct pt_regs *regs)
 	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
 		tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
 		if (!in_syscall(regs) || (flags & _TIF_SYSCALL_EMU))
-			return -1;
+			return NO_SYSCALL;
 	}
 
 	/* Do the secure computing after ptrace; failures should be fast. */
 	if (secure_computing() == -1)
-		return -1;
+		return NO_SYSCALL;
 
 	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
 		trace_sys_enter(regs, regs->syscallno);
-- 
2.27.0.383.g050319c2ae-goog


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  parent reply	other threads:[~2020-07-10 13:08 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-10 13:06 [PATCH v3 0/7] arm64: Fix single-step handling and syscall tracing Will Deacon
2020-07-10 13:06 ` [PATCH v3 1/7] arm64: ptrace: Consistently use pseudo-singlestep exceptions Will Deacon
2020-07-16  0:27   ` Sasha Levin
2020-07-10 13:06 ` [PATCH v3 2/7] arm64: ptrace: Override SPSR.SS when single-stepping is enabled Will Deacon
2020-07-16  0:27   ` Sasha Levin
2020-07-10 13:06 ` [PATCH v3 3/7] arm64: compat: Ensure upper 32 bits of x0 are zero on syscall return Will Deacon
2020-07-16  0:27   ` Sasha Levin
2020-07-10 13:06 ` [PATCH v3 4/7] arm64: ptrace: Add a comment describing our syscall entry/exit trap ABI Will Deacon
2020-07-10 13:07 ` [PATCH v3 5/7] arm64: syscall: Expand the comment about ptrace and syscall(-1) Will Deacon
2020-07-10 13:07 ` Will Deacon [this message]
2020-07-10 16:04   ` [PATCH v3 6/7] arm64: ptrace: Use NO_SYSCALL instead of -1 in syscall_trace_enter() Kees Cook
2020-07-10 16:11     ` Will Deacon
2020-07-13  2:32       ` Kees Cook
2020-07-10 13:07 ` [PATCH v3 7/7] arm64: Use test_tsk_thread_flag() for checking TIF_SINGLESTEP Will Deacon
2020-07-14 11:57 ` [PATCH v3 0/7] arm64: Fix single-step handling and syscall tracing Luis Machado
2020-07-15 12:25 ` Luis Machado

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