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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, David Howells <dhowells@redhat.com>,
        Masakazu Urade <urade.masakazu@jp.panasonic.com>,
        Koichi Yasutake <yasutake.koichi@jp.panasonic.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>
Subject: [PATCH 4.15 197/202] mn10300/misalignment: Use SIGSEGV SEGV_MAPERR to report a failed user copy
Date:   Thu, 15 Feb 2018 16:18:17 +0100
Message-Id: <20180215151722.967123072@linuxfoundation.org>
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4.15-stable 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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;