From: Mikolaj Kucharski <mikolaj@kucharski.name>
Subject: Re: FIX/WIP: Intermittent SIGSEGV in ansible-libssh-1.2.2
To: ports@openbsd.org
Cc: Denis Fondras <denis@openbsd.org>
Date: Mon, 18 Nov 2024 11:23:58 +0000

Please disregard this patch. The fix will be different.

On Thu, Nov 14, 2024 at 04:19:53PM +0000, Mikolaj Kucharski wrote:
> Hi,
> 
> I would like to use ansible-libssh and its exec_command(), but I am
> currently getting intermittent SIGSEGVs. I have work in progress patch
> from upstream inlined below.
> 
> My diff also enables debug package, but I am not sure does it add
> any value in Python modules, as I didn't see any improvement in gdb's
> bt output for compiled Python modules, so maybe it's not worth enabling.
> I would appreciate comment on this, if someone he deeper underanding of
> Python's compiled modules.
> 
> For me, the important bit is the upstream patch itself. The patch
> introduces a memory leak, but makes running exec_command() reliable
> without a crash.
> 
> 
> diff -ruN -xCVS -xTODO -xMakefile-testing py-ansible-libssh/Makefile py-ansible-libssh-new/Makefile
> --- py-ansible-libssh/Makefile	Thu Nov 14 16:03:33 2024
> +++ py-ansible-libssh-new/Makefile	Thu Nov 14 16:02:08 2024
> @@ -3,6 +3,7 @@
>  DISTNAME =		ansible-pylibssh-${MODPY_EGG_VERSION}
>  PKGNAME =		py-ansible-libssh-${MODPY_EGG_VERSION}
>  CATEGORIES =		sysutils
> +REVISION =		0
>  
>  MAINTAINER =		Denis Fondras <denis@openbsd.org>
>  
> @@ -17,6 +18,8 @@
>  MODULES =		lang/python
>  MODPY_PI =		Yes
>  MODPY_PYBUILD =		setuptools_scm
> +
> +DEBUG_PACKAGES =	${BUILD_PACKAGES}
>  
>  CFLAGS +=		-I${LOCALBASE}/include
>  BUILD_DEPENDS =		sysutils/py-expandvars${MODPY_FLAVOR} \
> diff -ruN -xCVS -xTODO -xMakefile-testing py-ansible-libssh/patches/patch-src_pylibsshext_channel_pyx py-ansible-libssh-new/patches/patch-src_pylibsshext_channel_pyx
> --- py-ansible-libssh/patches/patch-src_pylibsshext_channel_pyx	Thu Jan  1 00:00:00 1970
> +++ py-ansible-libssh-new/patches/patch-src_pylibsshext_channel_pyx	Thu Nov 14 15:59:37 2024
> @@ -0,0 +1,43 @@
> +- https://github.com/ansible/pylibssh/issues/645
> +- https://github.com/ansible/pylibssh/issues/657
> +- https://github.com/ansible/pylibssh/pull/658
> +
> +Index: src/pylibsshext/channel.pyx
> +--- src/pylibsshext/channel.pyx.orig
> ++++ src/pylibsshext/channel.pyx
> +@@ -20,6 +20,7 @@ import time
> + from io import BytesIO
> + 
> + from cpython.bytes cimport PyBytes_AS_STRING
> ++from cpython.mem cimport PyMem_Malloc
> + from libc.string cimport memset
> + 
> + from pylibsshext.errors cimport LibsshChannelException
> +@@ -166,12 +167,15 @@ cdef class Channel:
> +             raise LibsshChannelException("Failed to execute command [{0}]: [{1}]".format(command, rc))
> +         result = CompletedProcess(args=command, returncode=-1, stdout=b'', stderr=b'')
> + 
> +-        cdef callbacks.ssh_channel_callbacks_struct cb
> +-        memset(&cb, 0, sizeof(cb))
> ++        cb_size = sizeof(callbacks.ssh_channel_callbacks_struct)
> ++        cdef callbacks.ssh_channel_callbacks_struct *cb = <callbacks.ssh_channel_callbacks_struct *>PyMem_Malloc(cb_size)
> ++        if cb is NULL:
> ++            raise LibsshChannelException("Memory allocation error")
> ++        memset(cb, 0, cb_size)
> +         cb.channel_data_function = <callbacks.ssh_channel_data_callback>&_process_outputs
> +         cb.userdata = <void *>result
> +-        callbacks.ssh_callbacks_init(&cb)
> +-        callbacks.ssh_set_channel_callbacks(channel, &cb)
> ++        callbacks.ssh_callbacks_init(cb)
> ++        callbacks.ssh_set_channel_callbacks(channel, cb)
> + 
> +         libssh.ssh_channel_send_eof(channel)
> +         result.returncode = libssh.ssh_channel_get_exit_status(channel)
> +@@ -179,6 +183,7 @@ cdef class Channel:
> +             libssh.ssh_channel_close(channel)
> +             libssh.ssh_channel_free(channel)
> + 
> ++        # XXX leaking the memory of the callbacks
> +         return result
> + 
> +     def send_eof(self):
> 

-- 
Regards,
 Mikolaj