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ftrace: Protect direct_functions in update_ftrace_direct_mod

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Fix accessing the __rcu pointer direct_functions with RCU protection.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260730150411.88667-4-leon.hwang@linux.dev
Fixes: e93672f770 ("ftrace: Add update_ftrace_direct_mod function")
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Leon Hwang
2026-07-30 23:04:10 +08:00
committed by Steven Rostedt
parent f26e5fa75f
commit 092f8ec7db
1 changed files with 8 additions and 3 deletions
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11
kernel/trace/ftrace.c
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@@ -6617,6 +6617,7 @@ int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, b
.func = ftrace_stub,
.flags = FTRACE_OPS_FL_STUB,
};
struct ftrace_hash *direct_hash;
struct ftrace_hash *orig_hash;
unsigned long size, i;
int err = -EINVAL;
@@ -6627,8 +6628,6 @@ int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, b
return -EINVAL;
if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
return -EINVAL;
if (direct_functions == EMPTY_HASH)
return -EINVAL;
/*
* We can be called from within ops_func callback with direct_mutex
@@ -6636,6 +6635,12 @@ int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, b
*/
if (do_direct_lock)
mutex_lock(&direct_mutex);
else
lockdep_assert_held_once(&direct_mutex);
direct_hash = rcu_dereference_protected(direct_functions, lockdep_is_held(&direct_mutex));
if (direct_hash == EMPTY_HASH)
goto unlock;
orig_hash = ops->func_hash ? ops->func_hash->filter_hash : NULL;
if (!orig_hash)
@@ -6667,7 +6672,7 @@ int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, b
size = 1 << hash->size_bits;
for (i = 0; i < size; i++) {
hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
tmp = __ftrace_lookup_ip(direct_functions, entry->ip);
tmp = __ftrace_lookup_ip(direct_hash, entry->ip);
if (!tmp)
continue;
tmp->direct = entry->direct;