tracing: Fix possible memory leak in ftrace_regsiter_direct()
Commit Message
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
If ftrace_register_direct() called with a large number of target
functions (e.g. 65), the free_hash can be updated twice or more
in the ftrace_add_rec_direct() without freeing the previous hash
memory. Thus this can cause a memory leak.
Fix this issue by expanding the direct_hash at once before
adding the new entries.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes: f64dd4627ec6 ("ftrace: Add multi direct register/unregister interface")
Cc: stable@vger.kernel.org
---
kernel/trace/ftrace.c | 49 +++++++++++++++++++++++++++++++------------------
1 file changed, 31 insertions(+), 18 deletions(-)
@@ -2555,28 +2555,33 @@ unsigned long ftrace_find_rec_direct(unsigned long ip)
return entry->direct;
}
-static struct ftrace_func_entry*
-ftrace_add_rec_direct(unsigned long ip, unsigned long addr,
- struct ftrace_hash **free_hash)
+static struct ftrace_hash *ftrace_expand_direct(int inc_count)
{
- struct ftrace_func_entry *entry;
+ struct ftrace_hash *new_hash, *free_hash;
+ int size = ftrace_hash_empty(direct_functions) ? 0 :
+ direct_functions->count + inc_count;
- if (ftrace_hash_empty(direct_functions) ||
- direct_functions->count > 2 * (1 << direct_functions->size_bits)) {
- struct ftrace_hash *new_hash;
- int size = ftrace_hash_empty(direct_functions) ? 0 :
- direct_functions->count + 1;
+ if (!ftrace_hash_empty(direct_functions) &&
+ size <= 2 * (1 << direct_functions->size_bits))
+ return NULL;
- if (size < 32)
- size = 32;
+ if (size < 32)
+ size = 32;
- new_hash = dup_hash(direct_functions, size);
- if (!new_hash)
- return NULL;
+ new_hash = dup_hash(direct_functions, size);
+ if (!new_hash)
+ return ERR_PTR(-ENOMEM);
- *free_hash = direct_functions;
- direct_functions = new_hash;
- }
+ free_hash = direct_functions;
+ direct_functions = new_hash;
+
+ return free_hash;
+}
+
+static struct ftrace_func_entry*
+ftrace_add_rec_direct(unsigned long ip, unsigned long addr)
+{
+ struct ftrace_func_entry *entry;
entry = kmalloc(sizeof(*entry), GFP_KERNEL);
if (!entry)
@@ -5436,11 +5441,19 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
}
}
+ /* ... and prepare the insertion */
+ free_hash = ftrace_expand_direct(hash->count);
+ if (IS_ERR(free_hash)) {
+ err = PTR_ERR(free_hash);
+ free_hash = NULL;
+ goto out_unlock;
+ }
+
/* ... and insert them to direct_functions hash. */
err = -ENOMEM;
for (i = 0; i < size; i++) {
hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
- new = ftrace_add_rec_direct(entry->ip, addr, &free_hash);
+ new = ftrace_add_rec_direct(entry->ip, addr);
if (!new)
goto out_remove;
entry->direct = addr;