linux-kernel - [PATCH 3.16 173/192] s390/seccomp: fix error return for filtered system calls

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Message-ID: <lsq.1507553065.607535735@decadent.org.uk>
Date:   Mon, 09 Oct 2017 13:44:25 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Michael Holzheu" <holzheu@...ux.vnet.ibm.com>,
        "Jan Willeke" <willeke@...ibm.com>,
        "Martin Schwidefsky" <schwidefsky@...ibm.com>
Subject: [PATCH 3.16 173/192] s390/seccomp: fix error return for filtered
 system calls

3.16.49-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Willeke <willeke@...ibm.com>

commit dc295880c6752076f8b94ba3885d0bfff09e3e82 upstream.

The syscall_set_return_value function of s390 negates the error argument
before storing the value to the return register gpr2. This is incorrect,
the seccomp code already passes the negative error value.
Store the unmodified error value to gpr2.

Signed-off-by: Jan Willeke <willeke@...ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Cc: Michael Holzheu <holzheu@...ux.vnet.ibm.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/s390/include/asm/syscall.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -54,7 +54,7 @@ static inline void syscall_set_return_va
 					    struct pt_regs *regs,
 					    int error, long val)
 {
-	regs->gprs[2] = error ? -error : val;
+	regs->gprs[2] = error ? error : val;
 }
 
 static inline void syscall_get_arguments(struct task_struct *task,