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)? 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. Johan -- 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
