linux-kernel - [PATCH] PowerPC: kernel: memory access violation when rtas_data

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Message-ID: <5175FC36.4060308@asianux.com>
Date:	Tue, 23 Apr 2013 11:12:54 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC:	"paulus@...ba.org" <paulus@...ba.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Michael Ellerman <michael@...erman.id.au>,
	"sfr@...b.auug.org.au" <sfr@...b.auug.org.au>
Subject: [PATCH] PowerPC: kernel: memory access violation when rtas_data_buf
 contents are more than 1026


need set '\0' for 'local_buffer'.

SPLPAR_MAXLENGTH is 1026, RTAS_DATA_BUF_SIZE is 4096. so the contents of
rtas_data_buf may truncated in memcpy.

if contents are really truncated.
  the splpar_strlen is more than 1026. the next while loop checking will
  not find the end of buffer. that will cause memory access violation.


Signed-off-by: Chen Gang <gang.chen@...anux.com>
---
 arch/powerpc/kernel/lparcfg.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kernel/lparcfg.c b/arch/powerpc/kernel/lparcfg.c
index 801a757..d92f387 100644
--- a/arch/powerpc/kernel/lparcfg.c
+++ b/arch/powerpc/kernel/lparcfg.c
@@ -299,6 +299,7 @@ static void parse_system_parameter_string(struct seq_file *m)
 				__pa(rtas_data_buf),
 				RTAS_DATA_BUF_SIZE);
 	memcpy(local_buffer, rtas_data_buf, SPLPAR_MAXLENGTH);
+	local_buffer[SPLPAR_MAXLENGTH - 1] = '\0';
 	spin_unlock(&rtas_data_buf_lock);
 
 	if (call_status != 0) {
-- 
1.7.7.6
--
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