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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, "David Howells" <dhowells@redhat.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        "Masakazu Urade" <urade.masakazu@jp.panasonic.com>,
        "Koichi Yasutake" <yasutake.koichi@jp.panasonic.com>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
Message-ID: <lsq.1528380321.455976683@decadent.org.uk>
Subject: [PATCH 3.16 126/410] mn10300/misalignment: Use SIGSEGV
 SEGV_MAPERR to report a failed user copy
In-Reply-To: <lsq.1528380320.647747352@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

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

From: "Eric W. Biederman" <ebiederm@xmission.com>

commit 6ac1dc736b323011a55ecd1fc5897c24c4f77cbd upstream.

Setting si_code to 0 is the same a setting si_code to SI_USER which is definitely
not correct.  With si_code set to SI_USER si_pid and si_uid will be copied to
userspace instead of si_addr.  Which is very wrong.

So fix this by using a sensible si_code (SEGV_MAPERR) for this failure.

Fixes: b920de1b77b7 ("mn10300: add the MN10300/AM33 architecture to the kernel")
Cc: David Howells <dhowells@redhat.com>
Cc: Masakazu Urade <urade.masakazu@jp.panasonic.com>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 arch/mn10300/mm/misalignment.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mn10300/mm/misalignment.c
+++ b/arch/mn10300/mm/misalignment.c
@@ -437,7 +437,7 @@ transfer_failed:
 
 	info.si_signo	= SIGSEGV;
 	info.si_errno	= 0;
-	info.si_code	= 0;
+	info.si_code	= SEGV_MAPERR;
 	info.si_addr	= (void *) regs->pc;
 	force_sig_info(SIGSEGV, &info, current);
 	return;