From 5a64a79144e58a62426a34ef51b14e891f042fa2 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Nikola=20Forr=C3=B3?= <nforro@redhat.com>

Date: Tue, 17 Apr 2018 13:54:38 +0200

Subject: [PATCH 6/6] Increase maximal size of controller values

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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>

---

 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 efde2d1..1cd30df 100644

--- a/src/api.c

+++ b/src/api.c

@@ -1561,7 +1561,7 @@ 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;

 	}

@@ -2286,7 +2286,7 @@ static int cg_rd_ctrl_file(const char *subsys, const char *cgroup,

 	if (ctrl_file < 0)

 		return ECGROUPVALUENOTEXIST;

-	*value = calloc(CG_VALUE_MAX, 1);

+	*value = calloc(CG_CONTROL_VALUE_MAX, 1);

 	if (!*value) {

 		close(ctrl_file);

 		last_errno = errno;

@@ -2297,7 +2297,7 @@ static int cg_rd_ctrl_file(const char *subsys, const char *cgroup,

 	 * using %as or fread crashes when we try to read from files like

 	 * memory.stat

 	 */

-	ret = read(ctrl_file, *value, CG_VALUE_MAX-1);

+	ret = read(ctrl_file, *value, CG_CONTROL_VALUE_MAX-1);

 	if (ret < 0) {

 		free(*value);

 		*value = NULL;

diff --git a/src/libcgroup-internal.h b/src/libcgroup-internal.h

index 4c0f46c..3a8e336 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

@@ -73,7 +76,7 @@ __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 c03472a..0952823 100644

--- a/src/wrapper.c

+++ b/src/wrapper.c

@@ -132,10 +132,10 @@ 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;

 	}

@@ -145,8 +145,15 @@ 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++;

@@ -356,7 +363,7 @@ 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