Re: [syzbot] [rdma?] KASAN: slab-use-after-free Read in siw_query_port

[Guoqing Jiang <guoqing.jiang@linux.dev>]

On 5/12/23 15:10, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    16a8829130ca nfs: fix another case of NULL/IS_ERR confusio..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=162c0566280000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=8bc832f563d8bf38
> dashboard link: https://syzkaller.appspot.com/bug?extid=79f283f1f4ccc6e8b624
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/f8c18a31ba47/disk-16a88291.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/03a18f29b7e7/vmlinux-16a88291.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/1db2407ade1e/bzImage-16a88291.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+79f283f1f4ccc6e8b624@syzkaller.appspotmail.com
>
> xfrm0 speed is unknown, defaulting to 1000
> ==================================================================
> BUG: KASAN: slab-use-after-free in siw_query_port+0x37b/0x3e0 drivers/infiniband/sw/siw/siw_verbs.c:177
> Read of size 4 at addr ffff888034efa0e8 by task kworker/1:4/24211
>
> CPU: 1 PID: 24211 Comm: kworker/1:4 Not tainted 6.4.0-rc1-syzkaller-00012-g16a8829130ca #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
> Workqueue: infiniband ib_cache_event_task
> Call Trace:
>   <TASK>
>   __dump_stack lib/dump_stack.c:88 [inline]
>   dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
>   print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:351
>   print_report mm/kasan/report.c:462 [inline]
>   kasan_report+0x11c/0x130 mm/kasan/report.c:572
>   siw_query_port+0x37b/0x3e0 drivers/infiniband/sw/siw/siw_verbs.c:177
>   iw_query_port drivers/infiniband/core/device.c:2049 [inline]
>   ib_query_port drivers/infiniband/core/device.c:2090 [inline]
>   ib_query_port+0x3c4/0x8f0 drivers/infiniband/core/device.c:2082
>   ib_cache_update.part.0+0xcf/0x920 drivers/infiniband/core/cache.c:1487
>   ib_cache_update drivers/infiniband/core/cache.c:1561 [inline]
>   ib_cache_event_task+0x1b1/0x270 drivers/infiniband/core/cache.c:1561
>   process_one_work+0x99a/0x15e0 kernel/workqueue.c:2405
>   worker_thread+0x67d/0x10c0 kernel/workqueue.c:2552
>   kthread+0x344/0x440 kernel/kthread.c:379
>   ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
>   </TASK>

This might be similar as 390d3fdcae2d,  let me play with syzbot a bit 😉

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git 
for-rc

diff --git a/drivers/infiniband/core/device.c 
b/drivers/infiniband/core/device.c
index a666847bd714..9dd59f8d5f05 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -2016,6 +2016,7 @@static int iw_query_port(struct ib_device *device,
{
        struct in_device *inetdev;
        struct net_device *netdev;
+int ret;

        memset(port_attr, 0, sizeof(*port_attr));

@@ -2045,8 +2046,9 @@static int iw_query_port(struct ib_device *device,
                rcu_read_unlock();
        }

+ret = device->ops.query_port(device, port_num, port_attr);
        dev_put(netdev);
-       return device->ops.query_port(device, port_num, port_attr);
+return ret;
}

static int __ib_query_port(struct ib_device *device,