From: Michael Jeanson <mjeanson@efficios.com>
Date: Wed, 27 Jul 2022 14:54:53 +0000 (-0400)
Subject: fix: removed accidental VLA in _get_num_possible_cpus()
X-Git-Tag: v2.12.6~4
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=58683a1c4ed0ce78bf204d0ec999973959f70efa;p=lttng-ust.git

fix: removed accidental VLA in _get_num_possible_cpus()

The LTTNG_UST_PAGE_SIZE define can either point to a literal value or
the sysconf() function making buf[] a VLA. Replace this by a
cpumask specifc define that will always be a literal value.

Change-Id: I8d329f314878e8018939f979861918969e3ec8ac
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/libringbuffer/smp.c b/libringbuffer/smp.c
index 8b66b9e8..966556dc 100644
--- a/libringbuffer/smp.c
+++ b/libringbuffer/smp.c
@@ -30,6 +30,7 @@
 #include <stdlib.h>
 #include <unistd.h>
 
+#include "align.h"
 #include "smp.h"
 #include "usterr-signal-safe.h"
 
@@ -206,11 +207,10 @@ error:
 void _get_num_possible_cpus(void)
 {
 	int ret;
-	int buf_len = sysconf(_SC_PAGE_SIZE);
-	char buf[buf_len];
+	char buf[LTTNG_UST_CPUMASK_SIZE];
 
 	/* Get the possible cpu mask from sysfs, fallback to sysconf. */
-	ret = get_possible_cpu_mask_from_sysfs((char *) &buf, buf_len);
+	ret = get_possible_cpu_mask_from_sysfs((char *) &buf, LTTNG_UST_CPUMASK_SIZE);
 	if (ret <= 0)
 		goto fallback;
 
diff --git a/libringbuffer/smp.h b/libringbuffer/smp.h
index 1a880994..0db9e841 100644
--- a/libringbuffer/smp.h
+++ b/libringbuffer/smp.h
@@ -31,6 +31,8 @@
 
 extern int __num_possible_cpus;
 
+#define LTTNG_UST_CPUMASK_SIZE 4096
+
 /*
  * Get the CPU possible mask string from sysfs.
  *