ocfs2: incorrect check for debugfs returns

debugfs_create_dir and debugfs_create_file may return -ENODEV when debugfs
is not configured, so the return value should be checked against
ERROR_VALUE as well, otherwise the later dereference of the dentry pointer
would crash the kernel.

This patch tries to solve this problem by fixing certain checks. However,
I have that found other call sites are protected by #ifdef CONFIG_DEBUG_FS.
In current implementation, if CONFIG_DEBUG_FS is defined, then the above
two functions will never return any ERROR_VALUE. So another possibility
to fix this is to surround all the buggy checks/functions with the same
#ifdef CONFIG_DEBUG_FS. But I'm not sure if this would break any functionality,
as only OCFS2_FS_STATS declares dependency on DEBUG_FS.

Signed-off-by: Chengyu Song <csong84@gatech.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 37 insertions, 16 deletions

diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
index 16eff45727ee..8e19b9d7aba8 100644
--- a/fs/ocfs2/cluster/heartbeat.c
+++ b/fs/ocfs2/cluster/heartbeat.c
@@ -1312,7 +1312,9 @@ static int o2hb_debug_init(void)
         int ret = -ENOMEM;
 
         o2hb_debug_dir = debugfs_create_dir(O2HB_DEBUG_DIR, NULL);
-        if (!o2hb_debug_dir) {
+        if (IS_ERR_OR_NULL(o2hb_debug_dir)) {
+                ret = o2hb_debug_dir ?
+                        PTR_ERR(o2hb_debug_dir) : -ENOMEM;
                 mlog_errno(ret);
                 goto bail;
         }
@@ -1325,7 +1327,9 @@ static int o2hb_debug_init(void)
                                                  sizeof(o2hb_live_node_bitmap),
                                                  O2NM_MAX_NODES,
                                                  o2hb_live_node_bitmap);
-        if (!o2hb_debug_livenodes) {
+        if (IS_ERR_OR_NULL(o2hb_debug_livenodes)) {
+                ret = o2hb_debug_livenodes ?
+                        PTR_ERR(o2hb_debug_livenodes) : -ENOMEM;
                 mlog_errno(ret);
                 goto bail;
         }
@@ -1338,7 +1342,9 @@ static int o2hb_debug_init(void)
                                                    sizeof(o2hb_live_region_bitmap),
                                                    O2NM_MAX_REGIONS,
                                                    o2hb_live_region_bitmap);
-        if (!o2hb_debug_liveregions) {
+        if (IS_ERR_OR_NULL(o2hb_debug_liveregions)) {
+                ret = o2hb_debug_liveregions ?
+                        PTR_ERR(o2hb_debug_liveregions) : -ENOMEM;
                 mlog_errno(ret);
                 goto bail;
         }
@@ -1352,7 +1358,9 @@ static int o2hb_debug_init(void)
                                           sizeof(o2hb_quorum_region_bitmap),
                                           O2NM_MAX_REGIONS,
                                           o2hb_quorum_region_bitmap);
-        if (!o2hb_debug_quorumregions) {
+        if (IS_ERR_OR_NULL(o2hb_debug_quorumregions)) {
+                ret = o2hb_debug_quorumregions ?
+                        PTR_ERR(o2hb_debug_quorumregions) : -ENOMEM;
                 mlog_errno(ret);
                 goto bail;
         }
@@ -1366,7 +1374,9 @@ static int o2hb_debug_init(void)
                                           sizeof(o2hb_failed_region_bitmap),
                                           O2NM_MAX_REGIONS,
                                           o2hb_failed_region_bitmap);
-        if (!o2hb_debug_failedregions) {
+        if (IS_ERR_OR_NULL(o2hb_debug_failedregions)) {
+                ret = o2hb_debug_failedregions ?
+                        PTR_ERR(o2hb_debug_failedregions) : -ENOMEM;
                 mlog_errno(ret);
                 goto bail;
         }
@@ -2000,7 +2010,8 @@ static int o2hb_debug_region_init(struct o2hb_region *reg, struct dentry *dir)
 
         reg->hr_debug_dir =
                 debugfs_create_dir(config_item_name(&reg->hr_item), dir);
-        if (!reg->hr_debug_dir) {
+        if (IS_ERR_OR_NULL(reg->hr_debug_dir)) {
+                ret = reg->hr_debug_dir ? PTR_ERR(reg->hr_debug_dir) : -ENOMEM;
                 mlog_errno(ret);
                 goto bail;
         }
@@ -2013,7 +2024,9 @@ static int o2hb_debug_region_init(struct o2hb_region *reg, struct dentry *dir)
                                           O2HB_DB_TYPE_REGION_LIVENODES,
                                           sizeof(reg->hr_live_node_bitmap),
                                           O2NM_MAX_NODES, reg);
-        if (!reg->hr_debug_livenodes) {
+        if (IS_ERR_OR_NULL(reg->hr_debug_livenodes)) {
+                ret = reg->hr_debug_livenodes ?
+                        PTR_ERR(reg->hr_debug_livenodes) : -ENOMEM;
                 mlog_errno(ret);
                 goto bail;
         }
@@ -2025,7 +2038,9 @@ static int o2hb_debug_region_init(struct o2hb_region *reg, struct dentry *dir)
                                           sizeof(*(reg->hr_db_regnum)),
                                           O2HB_DB_TYPE_REGION_NUMBER,
                                           0, O2NM_MAX_NODES, reg);
-        if (!reg->hr_debug_regnum) {
+        if (IS_ERR_OR_NULL(reg->hr_debug_regnum)) {
+                ret = reg->hr_debug_regnum ?
+                        PTR_ERR(reg->hr_debug_regnum) : -ENOMEM;
                 mlog_errno(ret);
                 goto bail;
         }
@@ -2037,7 +2052,9 @@ static int o2hb_debug_region_init(struct o2hb_region *reg, struct dentry *dir)
                                           sizeof(*(reg->hr_db_elapsed_time)),
                                           O2HB_DB_TYPE_REGION_ELAPSED_TIME,
                                           0, 0, reg);
-        if (!reg->hr_debug_elapsed_time) {
+        if (IS_ERR_OR_NULL(reg->hr_debug_elapsed_time)) {
+                ret = reg->hr_debug_elapsed_time ?
+                        PTR_ERR(reg->hr_debug_elapsed_time) : -ENOMEM;
                 mlog_errno(ret);
                 goto bail;
         }
@@ -2049,13 +2066,16 @@ static int o2hb_debug_region_init(struct o2hb_region *reg, struct dentry *dir)
                                           sizeof(*(reg->hr_db_pinned)),
                                           O2HB_DB_TYPE_REGION_PINNED,
                                           0, 0, reg);
-        if (!reg->hr_debug_pinned) {
+        if (IS_ERR_OR_NULL(reg->hr_debug_pinned)) {
+                ret = reg->hr_debug_pinned ?
+                        PTR_ERR(reg->hr_debug_pinned) : -ENOMEM;
                 mlog_errno(ret);
                 goto bail;
         }
 
-        ret = 0;
+        return 0;
 bail:
+        debugfs_remove_recursive(reg->hr_debug_dir);
         return ret;
 }
 
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 11849a44dc5a..23adcbf374d3 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -2954,7 +2954,7 @@ static int ocfs2_dlm_init_debug(struct ocfs2_super *osb)
                                                          osb->osb_debug_root,
                                                          osb,
                                                          &ocfs2_dlm_debug_fops);
-        if (!dlm_debug->d_locking_state) {
+        if (IS_ERR_OR_NULL(dlm_debug->d_locking_state)) {
                 ret = -EINVAL;
                 mlog(ML_ERROR,
                      "Unable to create locking state debugfs file.\n");
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 26675185b886..fb43de586791 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1112,7 +1112,7 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
 
         osb->osb_debug_root = debugfs_create_dir(osb->uuid_str,
                                                  ocfs2_debugfs_root);
-        if (!osb->osb_debug_root) {
+        if (IS_ERR_OR_NULL(osb->osb_debug_root)) {
                 status = -EINVAL;
                 mlog(ML_ERROR, "Unable to create per-mount debugfs root.\n");
                 goto read_super_error;
@@ -1122,7 +1122,7 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
                                             osb->osb_debug_root,
                                             osb,
                                             &ocfs2_osb_debug_fops);
-        if (!osb->osb_ctxt) {
+        if (IS_ERR_OR_NULL(osb->osb_ctxt)) {
                 status = -EINVAL;
                 mlog_errno(status);
                 goto read_super_error;
@@ -1606,8 +1606,9 @@ static int __init ocfs2_init(void)
         }
 
         ocfs2_debugfs_root = debugfs_create_dir("ocfs2", NULL);
-        if (!ocfs2_debugfs_root) {
-                status = -ENOMEM;
+        if (IS_ERR_OR_NULL(ocfs2_debugfs_root)) {
+                status = ocfs2_debugfs_root ?
+                        PTR_ERR(ocfs2_debugfs_root) : -ENOMEM;
                 mlog(ML_ERROR, "Unable to create ocfs2 debugfs root.\n");
                 goto out4;
         }