ksym_tracer: Fix memory leak

- When remove a filter, we leak entry->ksym_hbp->info.name.

- With CONFIG_FTRAC_SELFTEST enabled, we leak ->info.name:
    # echo ksym_tracer > current_tracer
    # echo 'ksym_selftest_dummy:rw-' > ksym_trace_filter
    # echo nop > current_tracer

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A52E328.8010200@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 27 insertions, 34 deletions

diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index 891e3b86b3f6..7d349d34a0d1 100644
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -179,7 +179,7 @@ static int parse_ksym_trace_str(char *input_string, char **ksymname,
 int process_new_ksym_entry(char *ksymname, int op, unsigned long addr)
 {
         struct trace_ksym *entry;
-        int ret;
+        int ret = -ENOMEM;
 
         if (ksym_filter_entry_count >= KSYM_TRACER_MAX) {
                 printk(KERN_ERR "ksym_tracer: Maximum limit:(%d) reached. No"
@@ -193,12 +193,13 @@ int process_new_ksym_entry(char *ksymname, int op, unsigned long addr)
                 return -ENOMEM;
 
         entry->ksym_hbp = kzalloc(sizeof(struct hw_breakpoint), GFP_KERNEL);
-        if (!entry->ksym_hbp) {
-                kfree(entry);
-                return -ENOMEM;
-        }
+        if (!entry->ksym_hbp)
+                goto err;
+
+        entry->ksym_hbp->info.name = kstrdup(ksymname, GFP_KERNEL);
+        if (!entry->ksym_hbp->info.name)
+                goto err;
 
-        entry->ksym_hbp->info.name = ksymname;
         entry->ksym_hbp->info.type = op;
         entry->ksym_addr = entry->ksym_hbp->info.address = addr;
 #ifdef CONFIG_X86
@@ -210,14 +211,18 @@ int process_new_ksym_entry(char *ksymname, int op, unsigned long addr)
         if (ret < 0) {
                 printk(KERN_INFO "ksym_tracer request failed. Try again"
                                         " later!!\n");
-                kfree(entry->ksym_hbp);
-                kfree(entry);
-                return -EAGAIN;
+                ret = -EAGAIN;
+                goto err;
         }
         hlist_add_head_rcu(&(entry->ksym_hlist), &ksym_filter_head);
         ksym_filter_entry_count++;
-
         return 0;
+err:
+        if (entry->ksym_hbp)
+                kfree(entry->ksym_hbp->info.name);
+        kfree(entry->ksym_hbp);
+        kfree(entry);
+        return ret;
 }
 
 static ssize_t ksym_trace_filter_read(struct file *filp, char __user *ubuf,
@@ -289,7 +294,7 @@ static ssize_t ksym_trace_filter_write(struct file *file,
                         if (entry->ksym_hbp->info.type != op)
                                 changed = 1;
                         else
-                                goto err_ret;
+                                goto out;
                         break;
                 }
         }
@@ -298,34 +303,29 @@ static ssize_t ksym_trace_filter_write(struct file *file,
                 entry->ksym_hbp->info.type = op;
                 if (op > 0) {
                         ret = register_kernel_hw_breakpoint(entry->ksym_hbp);
-                        if (ret == 0) {
-                                ret = count;
-                                goto unlock_ret_path;
-                        }
-                } else
-                        ret = count;
+                        if (ret == 0)
+                                goto out;
+                }
                 ksym_filter_entry_count--;
                 hlist_del_rcu(&(entry->ksym_hlist));
                 synchronize_rcu();
+                kfree(entry->ksym_hbp->info.name);
                 kfree(entry->ksym_hbp);
                 kfree(entry);
-                goto err_ret;
+                goto out;
         } else {
                 /* Check for malformed request: (4) */
                 if (op == 0)
-                        goto err_ret;
+                        goto out;
                 ret = process_new_ksym_entry(ksymname, op, ksym_addr);
-                if (ret)
-                        goto err_ret;
         }
-        ret = count;
-        goto unlock_ret_path;
+out:
+        mutex_unlock(&ksym_tracer_mutex);
 
-err_ret:
         kfree(input_string);
 
-unlock_ret_path:
-        mutex_unlock(&ksym_tracer_mutex);
+        if (!ret)
+                ret = count;
         return ret;
 }
 
@@ -349,14 +349,7 @@ static void ksym_trace_reset(struct trace_array *tr)
                 ksym_filter_entry_count--;
                 hlist_del_rcu(&(entry->ksym_hlist));
                 synchronize_rcu();
-                /* Free the 'input_string' only if reset
-                 * after startup self-test
-                 */
-#ifdef CONFIG_FTRACE_SELFTEST
-                if (strncmp(entry->ksym_hbp->info.name, KSYM_SELFTEST_ENTRY,
-                                        strlen(KSYM_SELFTEST_ENTRY)) != 0)
-#endif /* CONFIG_FTRACE_SELFTEST*/
-                        kfree(entry->ksym_hbp->info.name);
+                kfree(entry->ksym_hbp->info.name);
                 kfree(entry->ksym_hbp);
                 kfree(entry);
         }