Subject: [PATCH] PowerPC: kernel: memory access violation when rtas_data_buf contents are more than 1026

From: Chen Gang <[email-masked]>
Date: Tue, 23 Apr 2013 11:12:54 +0800

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 <[email-masked]>
---
 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