linux-kernel - 4.3 serial driver crashes with console shortly after boot

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20151110002939.GG3533@two.firstfloor.org>
Date:	Tue, 10 Nov 2015 01:29:39 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	gregkh@...uxfoundation.org, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org, peter@...leysoftware.com
Subject: 4.3 serial driver crashes with console shortly after boot

Hi,

With 4.3 an x86 server is always crashing roughly a minute after boot
in __uart_start/uart_tx_stopped. This is repeatable over multiple boots.

The back trace is
flush_to_ldisc->n_tty_receive_buf2->n_tty_receive_buf_common->
commit_echoes-> uart_flush_chars->uart_start

It seems to follow a bad pointer here 

ffffffff813bbdfa:       f6 80 f4 01 00 00 01    testb  $0x1,0x1f4(%rax)
<---
ffffffff813bbe01:       74 01                   je     ffffffff813bbe04
<__uart_start.isra.1+0x24>

Unfortunately I don't have the contents of RAX which scrolled away,
but since CR2 is 1f4 I suspect it's NUL.

It seems to depend on the order of the console=... arguments on the
kernel command line. With console=tty0 console=ttyS0,115200n8 it
crashes, but when reversing the options it does not crash.

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/