From: Nikola Forró <nforro@redhat.com>
Date: Thu, 16 Jan 2020 17:43:54 +0000 (+0100)
Subject: Increase maximal size of controller values
X-Git-Tag: v0.42.1~1^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d0f9d063c95fadfb56429d6a022e414438af19ef;p=thirdparty%2Flibcgroup.git

Increase maximal size of controller values

Maximal length of a controller value is determined by CG_VALUE_MAX,
which is equal to 100. That is not sufficient in some cases.

Add new constant CG_CONTROL_VALUE_MAX (to prevent breaking current API)
and set it to 4096, which is usually equal to the amount of bytes that
can be written to a sysctl file directly.

Add warning message about exceeding the limit while parsing
configuration file.

Signed-off-by: Nikola Forró <nforro@redhat.com>
Reviewed-by: Tom Hromatka <tom.hromatka@oracle.com>
---

diff --git a/src/api.c b/src/api.c
index f15d93de..24ae48d3 100644
--- a/src/api.c
+++ b/src/api.c
@@ -1753,7 +1753,7 @@ static int cgroup_copy_controller_values(struct cgroup_controller *dst,
 		}
 
 		dst_val = dst->values[i];
-		strncpy(dst_val->value, src_val->value, CG_VALUE_MAX);
+		strncpy(dst_val->value, src_val->value, CG_CONTROL_VALUE_MAX);
 		strncpy(dst_val->name, src_val->name, FILENAME_MAX);
 		dst_val->dirty = src_val->dirty;
 	}
@@ -2486,7 +2486,7 @@ static int cg_rd_ctrl_file(const char *subsys, const char *cgroup,
 	if (!ctrl_file)
 		return ECGROUPVALUENOTEXIST;
 
-	*value = calloc(CG_VALUE_MAX, 1);
+	*value = calloc(CG_CONTROL_VALUE_MAX, 1);
 	if (!*value) {
 		fclose(ctrl_file);
 		last_errno = errno;
@@ -2497,7 +2497,7 @@ static int cg_rd_ctrl_file(const char *subsys, const char *cgroup,
 	 * using %as crashes when we try to read from files like
 	 * memory.stat
 	 */
-	ret = fread(*value, 1, CG_VALUE_MAX-1, ctrl_file);
+	ret = fread(*value, 1, CG_CONTROL_VALUE_MAX-1, ctrl_file);
 	if (ret < 0) {
 		free(*value);
 		*value = NULL;
diff --git a/src/libcgroup-internal.h b/src/libcgroup-internal.h
index 767cf196..e31df512 100644
--- a/src/libcgroup-internal.h
+++ b/src/libcgroup-internal.h
@@ -32,6 +32,9 @@ __BEGIN_DECLS
 /* Estimated number of groups created */
 #define MAX_GROUP_ELEMENTS	128
 
+/* Maximum length of a value */
+#define CG_CONTROL_VALUE_MAX 4096
+
 #define CG_NV_MAX 100
 #define CG_CONTROLLER_MAX 100
 #define CG_OPTIONS_MAX 100
@@ -80,7 +83,7 @@ __BEGIN_DECLS
 
 struct control_value {
 	char name[FILENAME_MAX];
-	char value[CG_VALUE_MAX];
+	char value[CG_CONTROL_VALUE_MAX];
 	bool dirty;
 };
 
diff --git a/src/tools/cgset.c b/src/tools/cgset.c
index 22397865..ddaeac43 100644
--- a/src/tools/cgset.c
+++ b/src/tools/cgset.c
@@ -151,8 +151,8 @@ int main(int argc, char *argv[])
 				goto err;
 			}
 
-			strncpy(name_value[nv_number].value, buf, CG_VALUE_MAX);
-			name_value[nv_number].value[CG_VALUE_MAX-1] = '\0';
+			strncpy(name_value[nv_number].value, buf, CG_CONTROL_VALUE_MAX);
+			name_value[nv_number].value[CG_CONTROL_VALUE_MAX-1] = '\0';
 
 			nv_number++;
 			break;
diff --git a/src/wrapper.c b/src/wrapper.c
index 20ecc139..b7932545 100644
--- a/src/wrapper.c
+++ b/src/wrapper.c
@@ -182,10 +182,10 @@ int cgroup_add_value_string(struct cgroup_controller *controller,
 	if (!controller)
 		return ECGINVAL;
 
-	if (controller->index >= CG_VALUE_MAX)
+	if (controller->index >= CG_NV_MAX)
 		return ECGMAXVALUESEXCEEDED;
 
-	for (i = 0; i < controller->index && i < CG_VALUE_MAX; i++) {
+	for (i = 0; i < controller->index && i < CG_NV_MAX; i++) {
 		if (!strcmp(controller->values[i]->name, name))
 			return ECGVALUEEXISTS;
 	}
@@ -195,6 +195,13 @@ int cgroup_add_value_string(struct cgroup_controller *controller,
 	if (!cntl_value)
 		return ECGCONTROLLERCREATEFAILED;
 
+	if (strlen(value) >= sizeof(cntl_value->value)) {
+		fprintf(stderr, "value exceeds the maximum of %d characters\n",
+			sizeof(cntl_value->value) - 1);
+		free(cntl_value);
+		return ECGCONFIGPARSEFAIL;
+	}
+
 	strncpy(cntl_value->name, name, sizeof(cntl_value->name));
 	cntl_value->name[sizeof(cntl_value->name)-1] = '\0';
 	strncpy(cntl_value->value, value, sizeof(cntl_value->value));