| Message ID | 20241231113731.277668-1-zilin@seu.edu.cn (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | d65474033740ded0a4fe9a097fce72328655b41d |
| Headers | show |
| Series | kernel/trace: Add READ_ONCE() when accessing fgraph_array[] | expand |
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index ddedcb509..30e3ddc8a 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -833,7 +833,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs #endif { for_each_set_bit(i, &bitmap, sizeof(bitmap) * BITS_PER_BYTE) { - struct fgraph_ops *gops = fgraph_array[i]; + struct fgraph_ops *gops = READ_ONCE(fgraph_array[i]); if (gops == &fgraph_stub) continue;
In __ftrace_return_to_handler(), a loop iterates over the fgraph_array[] elements, which are fgraph_ops. The loop checks if an element is a fgraph_stub to prevent using a fgraph_stub afterward. However, if the compiler reloads fgraph_array[] after this check, it might race with an update to fgraph_array[] that introduces a fgraph_stub. This could result in the stub being processed, but the stub contains a null "func_hash" field, leading to a NULL pointer dereference. To ensure that the gops compared against the fgraph_stub matches the gops processed later, add a READ_ONCE(). A similar patch appears in commit 63a8dfb ("function_graph: Add READ_ONCE() when accessing fgraph_array[]"). Signed-off-by: Zilin Guan <zilin@seu.edu.cn> --- kernel/trace/fgraph.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)