On Wed, Jun 21, 2017 at 10:31:39PM +0300, Luiz Augusto von Dentz wrote: > Hi Matias, > > On Wed, Jun 21, 2017 at 8:36 PM, Luiz Augusto von Dentz > <luiz.dentz@xxxxxxxxx> wrote: > > Hi Johan, > > > > On Wed, Jun 21, 2017 at 12:41 PM, Johan Hedberg <johan.hedberg@xxxxxxxxx> wrote: > >> Hi Matias, > >> > >> On Wed, Jun 21, 2017, Matias Karhumaa wrote: > >>> By sending OPP Put request before CONNECT we were able to cause > >>> SIGSEGV in obexd. Crash was caused by null pointer dereference. > >>> > >>> gdb output: > >>> > >>> Program received signal SIGSEGV, Segmentation fault. > >>> manager_request_authorization (transfer=transfer@entry=0x0, new_folder=new_folder@entry=0x7fffffffda18, new_name=new_name@entry=0x7fffffffda20) at obexd/src/manager.c:677 > >>> 677 struct obex_session *os = transfer->session; > >>> (gdb) bt > >>> *#0 manager_request_authorization (transfer=transfer@entry=0x0, new_folder=new_folder@entry=0x7fffffffda18, new_name=new_name@entry=0x7fffffffda20) at obexd/src/manager.c:677 > >>> *#1 0x000000000041b7a5 in opp_chkput (os=0x67de60, user_data=0x0) at obexd/plugins/opp.c:80 > >>> *#2 0x0000000000426cc5 in check_put (obex=0x678a50, req=0x679250, user_data=0x67de60) at obexd/src/obex.c:831 > >>> *#3 cmd_put (obex=0x678a50, req=0x679250, user_data=0x67de60) at obexd/src/obex.c:887 > >>> *#4 0x00000000004145e7 in handle_request (req=0x679250, obex=0x678a50) at gobex/gobex.c:1199 > >>> *#5 incoming_data (io=<optimized out>, cond=<optimized out>, user_data=0x678a50) at gobex/gobex.c:1375 > >>> *#6 0x00007ffff749204a in g_main_dispatch (context=0x674810) at /build/glib2.0-prJhLS/glib2.0-2.48.2/./glib/gmain.c:3154 > >>> *#7 g_main_context_dispatch (context=context@entry=0x674810) at /build/glib2.0-prJhLS/glib2.0-2.48.2/./glib/gmain.c:3769 > >>> *#8 0x00007ffff74923f0 in g_main_context_iterate (context=0x674810, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) > >>> at /build/glib2.0-prJhLS/glib2.0-2.48.2/./glib/gmain.c:3840 > >>> *#9 0x00007ffff7492712 in g_main_loop_run (loop=0x66fdf0) at /build/glib2.0-prJhLS/glib2.0-2.48.2/./glib/gmain.c:4034 > >>> *#10 0x000000000040dd0f in main (argc=1, argv=0x7fffffffde08) at obexd/src/main.c:322 > >>> > >>> Crash was found using Synopsys Defensics Obex Server test suite. > >>> --- > >>> obexd/src/obex.c | 2 +- > >>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>> > >>> diff --git a/obexd/src/obex.c b/obexd/src/obex.c > >>> index 788bffc..91fa838 100644 > >>> --- a/obexd/src/obex.c > >>> +++ b/obexd/src/obex.c > >>> @@ -825,7 +825,7 @@ static gboolean check_put(GObex *obex, GObexPacket *req, void *user_data) > >>> struct obex_session *os = user_data; > >>> int ret; > >>> > >>> - if (os->service->chkput == NULL) > >>> + if (os->service->chkput == NULL || os->service_data == NULL) > >>> goto done; > >> > >> As far as I understand, os->service_data is the OBEX service-specific > >> context, which I think can in principle validly be NULL. Also, isn't it > >> so that OBEX Object Push permits PUT without a preceding CONNECT (at > >> least that's what I remember from the times I was working with OBEX)? > > > > Yep, OPP can start a transfer without a CONNECT so the service_data > > will need to be instantiated directly on PUT if that wasn't created > > yet. > > > >> It seems to me that the bug is with opp.c passing the service_data to > >> manager_request_authorization(), and service_data is expected to be the > >> obex_transfer object. However, currently the code creates this object > >> only upon CONNECT (in opp_connect). > >> > >> I think one possible way to solve this would be to trigger a call to > >> os->service->connect if CONNECT hasn't been explicitly issued, however > >> then the code needs to track this in some other way since service_data > >> seems too unreliable. > > How about the following: > > https://gist.github.com/Vudentz/1736d6af9608b9332b93858d92a3feff Your fix seems solid to me and fixes the crash with OPP. I checked ftp.c also and saw potentially similar problem in ftp_chkput. Should we call os->service->connect also in case of OBEX_FTP? Best Regards, Matias Karhumaa -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
