powerpc/pseries/lparcfg: Fix possible overflow are more than 1026

commit 5676005acf26ab7e924a8438ea4746e47d405762 upstream.

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@asianux.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/powerpc/kernel/lparcfg.c b/arch/powerpc/kernel/lparcfg.c
index 826681dc342a6712e43fec6e8a1ff4058547fe3c..26af24bbaed495b7974808425dbefe231c0be066 100644 (file)
--- a/arch/powerpc/kernel/lparcfg.c
+++ b/arch/powerpc/kernel/lparcfg.c
@@ -375,6 +375,7 @@ 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) {