Commit dc033621 authored by Mike Marshall's avatar Mike Marshall

orangefs: clean up debugfs

We recently refactored the Orangefs debugfs code.
The refactor seemed to trigger dan.carpenter@oracle.com's
static tester to find a possible double-free in the code.

While designing the fix we saw a condition under which the
buffer being freed could also be overflowed.

We also realized how to rebuild the related debugfs file's
"contents" (a string) without deleting and re-creating the file.

This fix should eliminate the possible double-free, the
potential overflow and improve code readability.
Signed-off-by: default avatarMike Marshall <hubcap@omnibond.com>
Signed-off-by: default avatarMartin Brandenburg <martin@omnibond.com>
parent 804b1737
...@@ -141,6 +141,9 @@ static struct client_debug_mask client_debug_mask; ...@@ -141,6 +141,9 @@ static struct client_debug_mask client_debug_mask;
*/ */
static DEFINE_MUTEX(orangefs_debug_lock); static DEFINE_MUTEX(orangefs_debug_lock);
/* Used to protect data in ORANGEFS_KMOD_DEBUG_HELP_FILE */
static DEFINE_MUTEX(orangefs_help_file_lock);
/* /*
* initialize kmod debug operations, create orangefs debugfs dir and * initialize kmod debug operations, create orangefs debugfs dir and
* ORANGEFS_KMOD_DEBUG_HELP_FILE. * ORANGEFS_KMOD_DEBUG_HELP_FILE.
...@@ -289,6 +292,8 @@ static void *help_start(struct seq_file *m, loff_t *pos) ...@@ -289,6 +292,8 @@ static void *help_start(struct seq_file *m, loff_t *pos)
gossip_debug(GOSSIP_DEBUGFS_DEBUG, "help_start: start\n"); gossip_debug(GOSSIP_DEBUGFS_DEBUG, "help_start: start\n");
mutex_lock(&orangefs_help_file_lock);
if (*pos == 0) if (*pos == 0)
payload = m->private; payload = m->private;
...@@ -305,6 +310,7 @@ static void *help_next(struct seq_file *m, void *v, loff_t *pos) ...@@ -305,6 +310,7 @@ static void *help_next(struct seq_file *m, void *v, loff_t *pos)
static void help_stop(struct seq_file *m, void *p) static void help_stop(struct seq_file *m, void *p)
{ {
gossip_debug(GOSSIP_DEBUGFS_DEBUG, "help_stop: start\n"); gossip_debug(GOSSIP_DEBUGFS_DEBUG, "help_stop: start\n");
mutex_unlock(&orangefs_help_file_lock);
} }
static int help_show(struct seq_file *m, void *v) static int help_show(struct seq_file *m, void *v)
...@@ -610,31 +616,53 @@ static int orangefs_prepare_cdm_array(char *debug_array_string) ...@@ -610,31 +616,53 @@ static int orangefs_prepare_cdm_array(char *debug_array_string)
* /sys/kernel/debug/orangefs/debug-help can be catted to * /sys/kernel/debug/orangefs/debug-help can be catted to
* see all the available kernel and client debug keywords. * see all the available kernel and client debug keywords.
* *
* When the kernel boots, we have no idea what keywords the * When orangefs.ko initializes, we have no idea what keywords the
* client supports, nor their associated masks. * client supports, nor their associated masks.
* *
* We pass through this function once at boot and stamp a * We pass through this function once at module-load and stamp a
* boilerplate "we don't know" message for the client in the * boilerplate "we don't know" message for the client in the
* debug-help file. We pass through here again when the client * debug-help file. We pass through here again when the client
* starts and then we can fill out the debug-help file fully. * starts and then we can fill out the debug-help file fully.
* *
* The client might be restarted any number of times between * The client might be restarted any number of times between
* reboots, we only build the debug-help file the first time. * module reloads, we only build the debug-help file the first time.
*/ */
int orangefs_prepare_debugfs_help_string(int at_boot) int orangefs_prepare_debugfs_help_string(int at_boot)
{ {
int rc = -EINVAL;
int i;
int byte_count = 0;
char *client_title = "Client Debug Keywords:\n"; char *client_title = "Client Debug Keywords:\n";
char *kernel_title = "Kernel Debug Keywords:\n"; char *kernel_title = "Kernel Debug Keywords:\n";
size_t string_size = DEBUG_HELP_STRING_SIZE;
size_t result_size;
size_t i;
char *new;
int rc = -EINVAL;
gossip_debug(GOSSIP_UTILS_DEBUG, "%s: start\n", __func__); gossip_debug(GOSSIP_UTILS_DEBUG, "%s: start\n", __func__);
if (at_boot) { if (at_boot)
byte_count += strlen(HELP_STRING_UNINITIALIZED);
client_title = HELP_STRING_UNINITIALIZED; client_title = HELP_STRING_UNINITIALIZED;
} else {
/* build a new debug_help_string. */
new = kzalloc(DEBUG_HELP_STRING_SIZE, GFP_KERNEL);
if (!new) {
rc = -ENOMEM;
goto out;
}
/*
* strlcat(dst, src, size) will append at most
* "size - strlen(dst) - 1" bytes of src onto dst,
* null terminating the result, and return the total
* length of the string it tried to create.
*
* We'll just plow through here building our new debug
* help string and let strlcat take care of assuring that
* dst doesn't overflow.
*/
strlcat(new, client_title, string_size);
if (!at_boot) {
/* /*
* fill the client keyword/mask array and remember * fill the client keyword/mask array and remember
* how many elements there were. * how many elements there were.
...@@ -644,64 +672,40 @@ int orangefs_prepare_debugfs_help_string(int at_boot) ...@@ -644,64 +672,40 @@ int orangefs_prepare_debugfs_help_string(int at_boot)
if (cdm_element_count <= 0) if (cdm_element_count <= 0)
goto out; goto out;
/* Count the bytes destined for debug_help_string. */
byte_count += strlen(client_title);
for (i = 0; i < cdm_element_count; i++) { for (i = 0; i < cdm_element_count; i++) {
byte_count += strlen(cdm_array[i].keyword + 2); strlcat(new, "\t", string_size);
if (byte_count >= DEBUG_HELP_STRING_SIZE) { strlcat(new, cdm_array[i].keyword, string_size);
pr_info("%s: overflow 1!\n", __func__); strlcat(new, "\n", string_size);
goto out;
} }
} }
gossip_debug(GOSSIP_UTILS_DEBUG, strlcat(new, "\n", string_size);
"%s: cdm_element_count:%d:\n", strlcat(new, kernel_title, string_size);
__func__,
cdm_element_count);
}
byte_count += strlen(kernel_title);
for (i = 0; i < num_kmod_keyword_mask_map; i++) { for (i = 0; i < num_kmod_keyword_mask_map; i++) {
byte_count += strlcat(new, "\t", string_size);
strlen(s_kmod_keyword_mask_map[i].keyword + 2); strlcat(new, s_kmod_keyword_mask_map[i].keyword, string_size);
if (byte_count >= DEBUG_HELP_STRING_SIZE) { result_size = strlcat(new, "\n", string_size);
pr_info("%s: overflow 2!\n", __func__);
goto out;
}
} }
/* build debug_help_string. */ /* See if we tried to put too many bytes into "new"... */
debug_help_string = kzalloc(DEBUG_HELP_STRING_SIZE, GFP_KERNEL); if (result_size >= string_size) {
if (!debug_help_string) { kfree(new);
rc = -ENOMEM;
goto out; goto out;
} }
strcat(debug_help_string, client_title); if (at_boot) {
debug_help_string = new;
if (!at_boot) { } else {
for (i = 0; i < cdm_element_count; i++) { mutex_lock(&orangefs_help_file_lock);
strcat(debug_help_string, "\t"); memset(debug_help_string, 0, DEBUG_HELP_STRING_SIZE);
strcat(debug_help_string, cdm_array[i].keyword); strlcat(debug_help_string, new, string_size);
strcat(debug_help_string, "\n"); mutex_unlock(&orangefs_help_file_lock);
}
}
strcat(debug_help_string, "\n");
strcat(debug_help_string, kernel_title);
for (i = 0; i < num_kmod_keyword_mask_map; i++) {
strcat(debug_help_string, "\t");
strcat(debug_help_string, s_kmod_keyword_mask_map[i].keyword);
strcat(debug_help_string, "\n");
} }
rc = 0; rc = 0;
out: out: return rc;
return rc;
} }
...@@ -959,8 +963,12 @@ int orangefs_debugfs_new_client_string(void __user *arg) ...@@ -959,8 +963,12 @@ int orangefs_debugfs_new_client_string(void __user *arg)
ret = copy_from_user(&client_debug_array_string, ret = copy_from_user(&client_debug_array_string,
(void __user *)arg, (void __user *)arg,
ORANGEFS_MAX_DEBUG_STRING_LEN); ORANGEFS_MAX_DEBUG_STRING_LEN);
if (ret != 0)
if (ret != 0) {
pr_info("%s: CLIENT_STRING: copy_from_user failed\n",
__func__);
return -EIO; return -EIO;
}
/* /*
* The real client-core makes an effort to ensure * The real client-core makes an effort to ensure
...@@ -975,45 +983,18 @@ int orangefs_debugfs_new_client_string(void __user *arg) ...@@ -975,45 +983,18 @@ int orangefs_debugfs_new_client_string(void __user *arg)
client_debug_array_string[ORANGEFS_MAX_DEBUG_STRING_LEN - 1] = client_debug_array_string[ORANGEFS_MAX_DEBUG_STRING_LEN - 1] =
'\0'; '\0';
if (ret != 0) {
pr_info("%s: CLIENT_STRING: copy_from_user failed\n",
__func__);
return -EIO;
}
pr_info("%s: client debug array string has been received.\n", pr_info("%s: client debug array string has been received.\n",
__func__); __func__);
if (!help_string_initialized) { if (!help_string_initialized) {
/* Free the "we don't know yet" default string... */ /* Build a proper debug help string. */
kfree(debug_help_string);
/* build a proper debug help string */
if (orangefs_prepare_debugfs_help_string(0)) { if (orangefs_prepare_debugfs_help_string(0)) {
gossip_err("%s: no debug help string \n", gossip_err("%s: no debug help string \n",
__func__); __func__);
return -EIO; return -EIO;
} }
/* Replace the boilerplate boot-time debug-help file. */
debugfs_remove(help_file_dentry);
help_file_dentry =
debugfs_create_file(
ORANGEFS_KMOD_DEBUG_HELP_FILE,
0444,
debug_dir,
debug_help_string,
&debug_help_fops);
if (!help_file_dentry) {
gossip_err("%s: debugfs_create_file failed for"
" :%s:!\n",
__func__,
ORANGEFS_KMOD_DEBUG_HELP_FILE);
return -EIO;
}
} }
debug_mask_to_string(&client_debug_mask, 1); debug_mask_to_string(&client_debug_mask, 1);
......
...@@ -124,7 +124,7 @@ static int __init orangefs_init(void) ...@@ -124,7 +124,7 @@ static int __init orangefs_init(void)
* unknown at boot time. * unknown at boot time.
* *
* orangefs_prepare_debugfs_help_string will be used again * orangefs_prepare_debugfs_help_string will be used again
* later to rebuild the debug-help file after the client starts * later to rebuild the debug-help-string after the client starts
* and passes along the needed info. The argument signifies * and passes along the needed info. The argument signifies
* which time orangefs_prepare_debugfs_help_string is being * which time orangefs_prepare_debugfs_help_string is being
* called. * called.
...@@ -152,7 +152,9 @@ static int __init orangefs_init(void) ...@@ -152,7 +152,9 @@ static int __init orangefs_init(void)
ret = register_filesystem(&orangefs_fs_type); ret = register_filesystem(&orangefs_fs_type);
if (ret == 0) { if (ret == 0) {
pr_info("orangefs: module version %s loaded\n", ORANGEFS_VERSION); pr_info("%s: module version %s loaded\n",
__func__,
ORANGEFS_VERSION);
ret = 0; ret = 0;
goto out; goto out;
} }
......
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