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 f15d93def9144dce48cf793502a19993fbd32a6e..24ae48d359117de1022b6758368b120626b0d734 100644 (file)
--- 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 767cf196a0e7d550735fa030d9d0fc13667496c2..e31df512fcbe639bac70ffc7dd646150ff6d7c9a 100644 (file)
--- 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 223978656caeba1078646daf416cd455c21fc59b..ddaeac43be3ed395e856d29537b16e8e2ab3673f 100644 (file)
--- 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 20ecc13932a70d241343b19c11aa8e1d31d69efe..b7932545ebfa6a6dbb42ef8e361f92f65c0853e8 100644 (file)
--- 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));