Re: KASAN: use-after-free Read in tipc_udp_send_msg

[Eric Dumazet]

On Fri, Oct 18, 2024 at 7:00 AM Xia Chu <jiangmo9@xxxxxxxxx> wrote:
>
> Hi,
>
> We would like to report the following bug which has been found by our modified version of syzkaller.
>
> ======================================================
> description: KASAN: use-after-free Read in tipc_udp_send_msg
> affected file: net/tipc/udp_media.c
> kernel version: 4.20.0-rc6
> kernel commit: f5d582777bcb1c7ff19a5a2343f66ea01de401c6
> git tree: upstream
> kernel config: attached
> crash reproducer: attached
> ======================================================
> Crash log:
> BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
> BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:43 [inline]
> BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:969 [inline]
> BUG: KASAN: use-after-free in kfree_skb+0xb1/0x430 net/core/skbuff.c:655
> Read of size 4 at addr ffff88804efd5ba4 by task syz-executor.6/14936
>
> CPU: 0 PID: 14936 Comm: syz-executor.6 Not tainted 4.20.0-rc6+ #1

This is an old version of linux, not supported.

What do you expect from us ?