conf: fix run_script_argv()

Make sure that we allocate the buffer **after** we determined how much space we need in total. This fixes a SIGBUS/SIGSEGV Stéphane reported on aarch64 and armf. Reported-by: Stéphane Graber <stgraber@ubuntu.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: fix run_script_argv()
327cce76 · Christian Brauner · 47d4e397 · 327cce76
Unverified Commit 327cce76 authored Feb 16, 2018 by Christian Brauner
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Showing with 9 additions and 11 deletions

conf.c src/lxc/conf.c +9 -11

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--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -376,8 +376,6 @@ int run_script_argv(const char *name, unsigned int hook_version,
 	if (size > INT_MAX)
 		return -EFBIG;
-	buffer = alloca(size);
 	if (hook_version == 0) {
 		size += strlen(hookname);
 		size++;
@@ -390,19 +388,19 @@ int run_script_argv(const char *name, unsigned int hook_version,
 		if (size > INT_MAX)
 			return -EFBIG;
+	}
+	buffer = alloca(size);
+	if (hook_version == 0)
 		buf_pos = snprintf(buffer, size, "exec %s %s %s %s", script, name, section, hookname);
-		if (buf_pos < 0 || (size_t)buf_pos >= size) {
+	else
-			ERROR("Failed to create command line for script \"%s\"", script);
-			return -1;
-		}
-	} else {
 		buf_pos = snprintf(buffer, size, "exec %s", script);
-		if (buf_pos < 0 || (size_t)buf_pos >= size) {
+	if (buf_pos < 0 || (size_t)buf_pos >= size) {
-			ERROR("Failed to create command line for script \"%s\"", script);
+		ERROR("Failed to create command line for script \"%s\"", script);
-			return -1;
+		return -1;
-		}
+	}
+	if (hook_version == 1) {
 		ret = setenv("LXC_HOOK_TYPE", hookname, 1);
 		if (ret < 0) {
 			SYSERROR("Failed to set environment variable: "