From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Tue, 23 Jun 2015 21:27:31 +0000 (+0200)
Subject: Fix: get_cmdline_by_pid path length assumes a max pid of 65535
X-Git-Tag: v2.7.0-rc1~27
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=fae9a062a468c47fc71ef7aa96374bf9d87d137e;p=lttng-tools.git

Fix: get_cmdline_by_pid path length assumes a max pid of 65535

PROC(5) mentions that "On 64-bit systems, pid_max can be set to any
value up to 2^22 (PID_MAX_LIMIT, approximately 4 million)."

We use 32 bits for simplicity's sake.

Reported-by: Zhenyu Ren <zhenyu.ren@aliyun.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/include/lttng/constant.h b/include/lttng/constant.h
index ed3ebe073..10f1bf694 100644
--- a/include/lttng/constant.h
+++ b/include/lttng/constant.h
@@ -45,6 +45,13 @@
 /*
  * Event symbol length. Copied from LTTng kernel ABI.
  */
-#define LTTNG_SYMBOL_NAME_LEN             256
+#define LTTNG_SYMBOL_NAME_LEN			256
+
+/*
+ * PROC(5) mentions that PID_MAX_LIMIT may not exceed 2^22 on 64-bit HW.
+ * We prefer to use 32-bits for simplicity's sake.
+ */
+#define LTTNG_MAX_PID				INT32_MAX
+#define LTTNG_MAX_PID_STR			"2147483647"
 
 #endif /* LTTNG_CONSTANT_H */
diff --git a/src/bin/lttng/commands/list.c b/src/bin/lttng/commands/list.c
index b436777d6..1eac93487 100644
--- a/src/bin/lttng/commands/list.c
+++ b/src/bin/lttng/commands/list.c
@@ -25,6 +25,7 @@
 #include <assert.h>
 
 #include <common/mi-lttng.h>
+#include <lttng/constant.h>
 
 #include "../command.h"
 
@@ -106,7 +107,8 @@ static char *get_cmdline_by_pid(pid_t pid)
 	int ret;
 	FILE *fp = NULL;
 	char *cmdline = NULL;
-	char path[20];	/* Can't go bigger than /proc/65535/cmdline */
+	/* Can't go bigger than /proc/LTTNG_MAX_PID/cmdline */
+	char path[sizeof("/proc//cmdline") + sizeof(LTTNG_MAX_PID_STR) - 1];
 
 	snprintf(path, sizeof(path), "/proc/%d/cmdline", pid);
 	fp = fopen(path, "r");