> On May 6, 2020, at 1:19 AM, Walter Wu <walter-zh.wu@xxxxxxxxxxxx> wrote: > > This patchset improves KASAN reports by making them to have > call_rcu() call stack information. It is helpful for programmers > to solve use-after-free or double-free memory issue. > > The KASAN report was as follows(cleaned up slightly): > > BUG: KASAN: use-after-free in kasan_rcu_reclaim+0x58/0x60 > > Freed by task 0: > save_stack+0x24/0x50 > __kasan_slab_free+0x110/0x178 > kasan_slab_free+0x10/0x18 > kfree+0x98/0x270 > kasan_rcu_reclaim+0x1c/0x60 > rcu_core+0x8b4/0x10f8 > rcu_core_si+0xc/0x18 > efi_header_end+0x238/0xa6c > > First call_rcu() call stack: > save_stack+0x24/0x50 > kasan_record_callrcu+0xc8/0xd8 > call_rcu+0x190/0x580 > kasan_rcu_uaf+0x1d8/0x278 > > Last call_rcu() call stack: > (stack is not available) > > > Add new CONFIG option to record first and last call_rcu() call stack > and KASAN report prints two call_rcu() call stack. > > This option doesn't increase the cost of memory consumption. It is > only suitable for generic KASAN. I don’t understand why this needs to be a Kconfig option at all. If call_rcu() stacks are useful in general, then just always gather those information. How do developers judge if they need to select this option or not?
