Re: [Linux kernel bug] UBSAN: shift-out-of-bounds in dctcp_update_alpha

[Kuniyuki Iwashima]

From: Sam Sun <samsun1006219@xxxxxxxxx>
Date: Fri, 17 May 2024 13:03:18 +0800
> Dear developers and maintainers,
> 
> We encountered a shift-out-of-bounds bug while using our modified
> syzkaller. It was tested against the latest upstream kernel (6.9). The
> kernel was compiled by clang 14.0.0, and kernel config and C repro are
> attached to this email. Kernel crash log is listed below.
> ------------[ cut here ]------------
> UBSAN: shift-out-of-bounds in net/ipv4/tcp_dctcp.c:143:12

Just for the record, I posted a patch:

https://lore.kernel.org/netdev/20240517091626.32772-1-kuniyu@xxxxxxxxxx/