Re: [linus:master] [blk] 22465bbac5: BUG:KASAN:slab-use-after-free_in__cpuhp_state_add_instance_cpuslocked

Ming Lei
2024-12-18T02:01:17Z

On Tue, Dec 17, 2024 at 10:20:47PM +0800, kernel test robot wrote:
>
>
> Hello,
>
> kernel test robot noticed "BUG:KASAN:slab-use-after-free_in__cpuhp_state_add_instance_cpuslocked" on:
>
> commit: 22465bbac53c821319089016f268a2437de9b00a ("blk-mq: move cpuhp callback registering out of q->sysfs_lock")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>
> [test failed on linus/master 231825b2e1ff6ba799c5eaf396d3ab2354e37c6b]
> [test failed on linux-next/master 3e42dc9229c5950e84b1ed705f94ed75ed208228]
>
> in testcase: blktests
> version: blktests-x86_64-3617edd-1_20241105
> with following parameters:
>
> disk: 1SSD
> test: block-group-01
>
>
>
> config: x86_64-rhel-9.4-func
> compiler: gcc-12
> test machine: 4 threads Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz (Skylake) with 32G memory
>
> (please refer to attached dmesg/kmsg for entire log/backtrace)
>
>
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <oliver.sang@intel.com>
> | Closes: https://lore.kernel.org/oe-lkp/202412172217.b906db7c-lkp@intel.com
>
>
> [ 232.596698][ T3545] BUG: KASAN: slab-use-after-free in __cpuhp_state_add_instance_cpuslocked (include/linux/list.h:1026 kernel/cpu.c:2446)

Hello,

Thanks for the report!

Unfortunately I can't reproduce it in my test VM by running
'blktests block/030' with:

- two numa nodes
- enable CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION

But just figured out that one freed hctx still may stay in cpuhp cb list, can
you test the following patch?

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 92e8ddf34575..f655b34efffe 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -4421,7 +4421,8 @@ static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx(
/* reuse dead hctx first */
spin_lock(&q->unused_hctx_lock);
list_for_each_entry(tmp, &q->unused_hctx_list, hctx_list) {
- if (tmp->numa_node == node) {
+ if (tmp->numa_node == node &&
+ hlist_unhashed(&tmp->cpuhp_online)) {
hctx = tmp;
break;
}

thanks,
Ming