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tracing: Correct the refcount if the hist/hist_debug file fails to open

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The function event_{hist,hist_debug}_open() maintains the refcount of
'file->tr' and 'file' through tracing_open_file_tr(). However, it does
not roll back these counts on subsequent failure paths, resulting in a
refcount leak.

A very obvious case is that if the hist/hist_debug file belongs to a
specific instance, the refcount leak will prevent the deletion of that
instance, as it relies on the condition 'tr->ref == 1' within
__remove_instance().

Fix this by calling tracing_release_file_tr() on all failure paths in
event_{hist,hist_debug}_open() to correct the refcount.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Zheng Yejian <zhengyejian1@huawei.com>
Link: https://lore.kernel.org/20250314065335.1202817-1-wutengda@huaweicloud.com
Fixes: 1cc111b9cddc ("tracing: Fix uaf issue when open the hist or hist_debug file")
Signed-off-by: Tengda Wu <wutengda@huaweicloud.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Tengda Wu 2025-03-14 06:53:35 +00:00 committed by Steven Rostedt (Google)
parent 7eb172143d
commit 0b4ffbe488
1 changed files with 18 additions and 6 deletions
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24
kernel/trace/trace_events_hist.c
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@ -5689,12 +5689,16 @@ static int event_hist_open(struct inode *inode, struct file *file)
guard(mutex)(&event_mutex);
event_file = event_file_data(file);
if (!event_file)
return -ENODEV;
if (!event_file) {
ret = -ENODEV;
goto err;
}
hist_file = kzalloc(sizeof(*hist_file), GFP_KERNEL);
if (!hist_file)
return -ENOMEM;
if (!hist_file) {
ret = -ENOMEM;
goto err;
}
hist_file->file = file;
hist_file->last_act = get_hist_hit_count(event_file);
@ -5702,9 +5706,14 @@ static int event_hist_open(struct inode *inode, struct file *file)
/* Clear private_data to avoid warning in single_open() */
file->private_data = NULL;
ret = single_open(file, hist_show, hist_file);
if (ret)
if (ret) {
kfree(hist_file);
goto err;
}
return 0;
err:
tracing_release_file_tr(inode, file);
return ret;
}
@ -5979,7 +5988,10 @@ static int event_hist_debug_open(struct inode *inode, struct file *file)
/* Clear private_data to avoid warning in single_open() */
file->private_data = NULL;
return single_open(file, hist_debug_show, file);
ret = single_open(file, hist_debug_show, file);
if (ret)
tracing_release_file_tr(inode, file);
return ret;
}
const struct file_operations event_hist_debug_fops = {