6.12-stable review patch. If anyone has any objections, please let me know.
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From: Tengda Wu wutengda@huaweicloud.com
[ Upstream commit 0b4ffbe4888a2c71185eaf5c1a02dd3586a9bc04 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/trace/trace_events_hist.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index e07d75adab8e3..4ebafc655223a 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -5692,12 +5692,16 @@ 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); @@ -5705,9 +5709,14 @@ 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; }
@@ -5982,7 +5991,10 @@ 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 = {