| Message ID | 20250320122137.23635-1-wutengda@huaweicloud.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 7f81f27b1093e4895e87b74143c59c055c3b1906 |
| Headers | show |
| Series | tracing: Fix use-after-free in print_graph_function_flags during tracer switching | expand |
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index 71b2fb068b6b..f995bddf2ab0 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -1614,6 +1614,7 @@ void graph_trace_close(struct trace_iterator *iter) if (data) { free_percpu(data->cpu_data); kfree(data); + iter->private = NULL; } } diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c index c8bfa7310a91..40c39e946940 100644 --- a/kernel/trace/trace_irqsoff.c +++ b/kernel/trace/trace_irqsoff.c @@ -250,8 +250,6 @@ static void irqsoff_trace_open(struct trace_iterator *iter) { if (is_graph(iter->tr)) graph_trace_open(iter); - else - iter->private = NULL; } static void irqsoff_trace_close(struct trace_iterator *iter) diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index c9ba4259e03e..a0db3404f7f7 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -188,8 +188,6 @@ static void wakeup_trace_open(struct trace_iterator *iter) { if (is_graph(iter->tr)) graph_trace_open(iter); - else - iter->private = NULL; } static void wakeup_trace_close(struct trace_iterator *iter)
Kairui reported a UAF issue in print_graph_function_flags() during ftrace stress testing [1]. This issue can be reproduced if puting a 'mdelay(10)' after 'mutex_unlock(&trace_types_lock)' in s_start(), and executing the following script: $ echo function_graph > current_tracer $ cat trace > /dev/null & $ sleep 5 # Ensure the 'cat' reaches the 'mdelay(10)' point $ echo timerlat > current_tracer The root cause lies in the two calls to print_graph_function_flags within print_trace_line during each s_show(): * One through 'iter->trace->print_line()'; * Another through 'event->funcs->trace()', which is hidden in print_trace_fmt() before print_trace_line returns. Tracer switching only updates the former, while the latter continues to use the print_line function of the old tracer, which in the script above is print_graph_function_flags. Moreover, when switching from the 'function_graph' tracer to the 'timerlat' tracer, s_start only calls graph_trace_close of the 'function_graph' tracer to free 'iter->private', but does not set it to NULL. This provides an opportunity for 'event->funcs->trace()' to use an invalid 'iter->private'. To fix this issue, set 'iter->private' to NULL immediately after freeing it in graph_trace_close(), ensuring that an invalid pointer is not passed to other tracers. Additionally, clean up the unnecessary 'iter->private = NULL' during each 'cat trace' when using wakeup and irqsoff tracers. [1] https://lore.kernel.org/all/20231112150030.84609-1-ryncsn@gmail.com/ Fixes: eecb91b9f98d ("tracing: Fix memleak due to race between current_tracer and trace") Signed-off-by: Tengda Wu <wutengda@huaweicloud.com> Reported-by: Kairui Song <kasong@tencent.com> Closes: https://lore.kernel.org/all/CAMgjq7BW79KDSCyp+tZHjShSzHsScSiJxn5ffskp-QzVM06fxw@mail.gmail.com/ Cc: stable@vger.kernel.org # v6.5+ --- kernel/trace/trace_functions_graph.c | 1 + kernel/trace/trace_irqsoff.c | 2 -- kernel/trace/trace_sched_wakeup.c | 2 -- 3 files changed, 1 insertion(+), 4 deletions(-)