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 <nfo...@redhat.com>
---
src/api.c | 6 +++---
src/libcgroup-internal.h | 5 ++++-
src/tools/cgset.c | 4 ++--
src/wrapper.c | 17 ++++++++++++-----
4 files changed, 21 insertions(+), 11 deletions(-)
diff --git a/src/api.c b/src/api.c
index feee4e1..4913f8d 100644
--- a/src/api.c
+++ b/src/api.c
@@ -1689,7 +1689,7 @@ 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);
}
err:
@@ -2421,7 +2421,7 @@ 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;
@@ -2432,7 +2432,7 @@ 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 9875dd9..ad71451 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
/* Max number of mounted hierarchies. Event if one controller is mounted per
@@ -77,7 +80,7 @@ __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 ea9f90d..3d3c8cc 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 3a9331f..0fe80d0 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;
}
@@ -195,8 +195,15 @@ int cgroup_add_value_string(struct cgroup_controller
*controller,
if (!cntl_value)
return ECGCONTROLLERCREATEFAILED;
- strncpy(cntl_value->name, name, sizeof(cntl_value->name));
- strncpy(cntl_value->value, value, sizeof(cntl_value->value));
+ if (strlen(value) >= sizeof(cntl_value->value)) {
+ fprintf(stderr, "value exceeds the maximum of %d characters\n",
+ sizeof(cntl_value->value));
+ free(cntl_value);
+ return ECGCONFIGPARSEFAIL;
+ }
+
+ strncpy(cntl_value->name, name, sizeof(cntl_value->name) - 1);
+ strncpy(cntl_value->value, value, sizeof(cntl_value->value) - 1);
cntl_value->dirty = true;
controller->values[controller->index] = cntl_value;
controller->index++;
@@ -406,7 +413,7 @@ int cgroup_set_value_string(struct cgroup_controller
*controller,
for (i = 0; i < controller->index; i++) {
struct control_value *val = controller->values[i];
if (!strcmp(val->name, name)) {
- strncpy(val->value, value, CG_VALUE_MAX);
+ strncpy(val->value, value, CG_CONTROL_VALUE_MAX - 1);
val->dirty = true;
return 0;
}
--
2.17.0
------------------------------------------------------------------------------
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