On Mon, Jan 03, 2022 at 09:05:16AM -0800, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: a8ad9a2434dc Merge tag 'efi-urgent-for-v5.16-2' of git://g.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=10cf5253b00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=1a86c22260afac2f > dashboard link: https://syzkaller.appspot.com/bug?extid=e3f96c43d19782dd14a7 > 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. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+e3f96c43d19782dd14a7@xxxxxxxxxxxxxxxxxxxxxxxxx > > ================================================================== > BUG: KASAN: use-after-free in ucma_cleanup_multicast drivers/infiniband/core/ucma.c:491 [inline] > BUG: KASAN: use-after-free in ucma_destroy_private_ctx+0x914/0xb70 drivers/infiniband/core/ucma.c:579 > Read of size 8 at addr ffff88801bb74b00 by task syz-executor.1/25529 Jason, Can it be race between ucma_process_join() and "if (refcount_read(&ctx->ref))" check in ucma_destroy_private_ctx()? The ucma_process_join() grabbed ctx, but released it in error path, while ucma_destroy_private_ctx() was called without holding any locks? Thanks