sshd crash

[Tim Kientzle]

On Nov 1, 2013, at 3:02 PM, Ian Lepore <ian at freebsd.org> wrote:

> On Sat, 2013-11-02 at 02:40 +0800, Jia-Shiun Li wrote:
>> On Sat, Nov 2, 2013 at 1:53 AM, Ian Lepore <ian at freebsd.org> wrote:
>>> On Sat, 2013-11-02 at 01:44 +0800, Jia-Shiun Li wrote:
>>>> may I add: putty causes this to happen. mine 0.62. But ssh from another
>>>> FreeBSD host has no problem.
>>>> 
>>>> I suspect it to be some issues related to memory or malloc issues
>>>> specific to bbb. 'tmux a -d' without existing detached sessions
>>>> causes tmux client to core dump. But sshd and it are both fine on rpi.
>>>> 
>>>> -Jia-Shiun.
>>> 
>>> This is the first I've heard of being able to ssh to an arm platform
>>> that doesn't have PrivSep disabled, since about July or so.  I've never
>>> heard a report yet that anything on the client side could make a
>>> difference.
>>> 
>>> It's definitely not a beaglebone thing, it happens on every arm board
>>> I've got... dreamplug, rpi, bbw, imx53, wandboard.
>> 
>> 
>> Ok let me make sure I did not mix things up. ;)
>> 
>> IIRC  I once saw similar issue on rpi shortly. But after another
>> weekly update it was gone. I did not pay too much attention on rpi,
>> and thought it was bbb specific.
>> 
>> I did not change sshd_config, UsePrivilegeSeparation supposed
>> remaining on as default is.

I started looking into it a couple of months ago but didn't get
very far; Diane Bruce got a lot further than I did.

If I recall correctly, it started up when the malloc libc symbols
were changed.  That may have altered what malloc implementation
sshd used.

So it could be a long-standing stray write that jemalloc just
happens to detect.

It could also be related to locking (there's some multi-threaded
crypto code in sshd that may be involved).

Tim