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Re: (ITS#7249) slapd segfault with memberof overlay on frontend db
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On Friday 27 of April 2012 12:26:22, Howard Chu wrote:
> jvcelak@redhat.com wrote:
> >> What happens is that the memberof overlay, when stacked on the frontend
> >> database, keeps looping until the stack is exhausted, since internal
> >> modifications keep calling the frontend's modify hook rather than the
> >> actual one that needs to be called.
> >
> > I have no idea how to fix it. I probably do not understand the
> > manipulation
> > with BackedInfo structures fully.
> >
> > It is obious that it is caused by doing a search from the modrdn operation
> > callback memberof_res_modrdn() which is set up in memberof_op_modrdn().
> > Other backends does not call any backend operation at the same moment
> > (op->callback).
> >
> > Frontend fe_op_search() is called. It tries to choose the right backend
> > with select_backend(). Which returns the overlay backend (bi_type ==
> > "over"), over_op_walk() then selects fe_op_search() again, and we are
> > looping infinitely.
> >
> > I have no clue how to hide or temporarily deactivate the overlay in
> > memberof_res_modrdn() to make the select_backend() function to choose the
> > right underlaying backend. Or maybe I have choosen a wrong way of fixing
> > it.
> >
> > All ideas are welcomed. :-)
>
> The attached diff fixes this particular problem. I haven't spent any time to
> see if the other be_* invocations need to be protected the same way.
Thank you. I have added this check to another places (attaching patch). But
it seems that it is not sufficient. In certain situations I can still trigger
the segfault - from memberof_res_modrdn() by calling backend_attribute().
At a first glance, the circumstances are a little bit different but I see
no difference in the structures when calling the function with overlay
set on frontend and backend database. I hope I will have some time to look
at it soon.
(gdb) bt -30
#35697 0x00000000004d9368 in overlay_entry_get_ov (op=0x7fffe40028f0, dn=0x7ffff23d9050, oc=0x0, ad=0x9e8450, rw=0, e=0x7ffff23d8d28,
on=0x0) at ../../../servers/slapd/backover.c:364
#35698 0x00000000004d9460 in over_entry_get_rw (op=0x7fffe40028f0, dn=0x7ffff23d9050, oc=0x0, ad=0x9e8450, rw=0, e=0x7ffff23d8d28)
at ../../../servers/slapd/backover.c:396
#35699 0x00000000004dd448 in fe_entry_get_rw (op=0x7fffe40028f0, ndn=0x7ffff23d9050, oc=0x0, at=0x9e8450, rw=0, e=0x7ffff23d8d28)
at ../../../servers/slapd/frontend.c:62
#35700 0x00000000004d9368 in overlay_entry_get_ov (op=0x7fffe40028f0, dn=0x7ffff23d9050, oc=0x0, ad=0x9e8450, rw=0, e=0x7ffff23d8d28,
on=0x0) at ../../../servers/slapd/backover.c:364
#35701 0x00000000004d9460 in over_entry_get_rw (op=0x7fffe40028f0, dn=0x7ffff23d9050, oc=0x0, ad=0x9e8450, rw=0, e=0x7ffff23d8d28)
at ../../../servers/slapd/backover.c:396
#35702 0x00000000004dd448 in fe_entry_get_rw (op=0x7fffe40028f0, ndn=0x7ffff23d9050, oc=0x0, at=0x9e8450, rw=0, e=0x7ffff23d8d28)
at ../../../servers/slapd/frontend.c:62
#35703 0x00000000004d9368 in overlay_entry_get_ov (op=0x7fffe40028f0, dn=0x7ffff23d9050, oc=0x0, ad=0x9e8450, rw=0, e=0x7ffff23d8d28,
on=0x0) at ../../../servers/slapd/backover.c:364
#35704 0x00000000004d9460 in over_entry_get_rw (op=0x7fffe40028f0, dn=0x7ffff23d9050, oc=0x0, ad=0x9e8450, rw=0, e=0x7ffff23d8d28)
at ../../../servers/slapd/backover.c:396
#35705 0x00000000004dd448 in fe_entry_get_rw (op=0x7fffe40028f0, ndn=0x7ffff23d9050, oc=0x0, at=0x9e8450, rw=0, e=0x7ffff23d8d28)
at ../../../servers/slapd/frontend.c:62
#35706 0x00000000004d9368 in overlay_entry_get_ov (op=0x7fffe40028f0, dn=0x7ffff23d9050, oc=0x0, ad=0x9e8450, rw=0, e=0x7ffff23d8d28,
on=0x0) at ../../../servers/slapd/backover.c:364
#35707 0x00000000004d9460 in over_entry_get_rw (op=0x7fffe40028f0, dn=0x7ffff23d9050, oc=0x0, ad=0x9e8450, rw=0, e=0x7ffff23d8d28)
at ../../../servers/slapd/backover.c:396
#35708 0x000000000044fc46 in be_entry_get_rw (op=0x7fffe40028f0, ndn=0x7ffff23d9050, oc=0x0, at=0x9e8450, rw=0, e=0x7ffff23d8d28)
at ../../../servers/slapd/backend.c:1366
#35709 0x0000000000450990 in fe_acl_attribute (op=0x7fffe40028f0, target=0x0, edn=0x7ffff23d9050, entry_at=0x9e8450,
vals=0x7ffff23d9088, access=ACL_READ) at ../../../servers/slapd/backend.c:1658
#35710 0x00000000004d9cdb in over_acl_attribute (op=0x7fffe40028f0, target=0x0, entry_ndn=0x7ffff23d9050, entry_at=0x9e8450,
vals=0x7ffff23d9088, access=ACL_READ) at ../../../servers/slapd/backover.c:589
#35711 0x0000000000450ed5 in backend_attribute (op=0x7fffe40028f0, target=0x0, edn=0x7ffff23d9050, entry_at=0x9e8450,
vals=0x7ffff23d9088, access=ACL_READ) at ../../../servers/slapd/backend.c:1778
#35712 0x00000000005a4c9f in memberof_res_modrdn (op=0x7fffe40028f0, rs=0x7ffff23d9a60)
at ../../../../servers/slapd/overlays/memberof.c:1558
#35713 0x000000000045252c in slap_response_play (op=0x7fffe40028f0, rs=0x7ffff23d9a60) at ../../../servers/slapd/result.c:507
#35714 0x0000000000452768 in send_ldap_response (op=0x7fffe40028f0, rs=0x7ffff23d9a60) at ../../../servers/slapd/result.c:582
#35715 0x0000000000453952 in slap_send_ldap_result (op=0x7fffe40028f0, rs=0x7ffff23d9a60) at ../../../servers/slapd/result.c:860
#35716 0x000000000050dfa9 in bdb_modrdn (op=0x7fffe40028f0, rs=0x7ffff23d9a60) at ../../../../servers/slapd/back-bdb/modrdn.c:789
#35717 0x00000000004625be in fe_op_modrdn (op=0x7fffe40028f0, rs=0x7ffff23d9a60) at ../../../servers/slapd/modrdn.c:314
#35718 0x00000000004d9ed4 in overlay_op_walk (op=0x7fffe40028f0, rs=0x7ffff23d9a60, which=op_modrdn, oi=0x7fffe41050e0, on=0x0)
at ../../../servers/slapd/backover.c:671
#35719 0x00000000004da125 in over_op_func (op=0x7fffe40028f0, rs=0x7ffff23d9a60, which=op_modrdn)
at ../../../servers/slapd/backover.c:723
#35720 0x00000000004da2b2 in over_op_modrdn (op=0x7fffe40028f0, rs=0x7ffff23d9a60) at ../../../servers/slapd/backover.c:768
#35721 0x0000000000461d20 in do_modrdn (op=0x7fffe40028f0, rs=0x7ffff23d9a60) at ../../../servers/slapd/modrdn.c:186
#35722 0x000000000043a8df in connection_operation (ctx=0x7ffff23d9ba0, arg_v=0x7fffe40028f0)
at ../../../servers/slapd/connection.c:1150
#35723 0x000000000043ae9c in connection_read_thread (ctx=0x7ffff23d9ba0, argv=0x15) at ../../../servers/slapd/connection.c:1286
#35724 0x00000000005d12ce in ldap_int_thread_pool_wrapper (xpool=0x9b0bf0) at ../../../libraries/libldap_r/tpool.c:688
#35725 0x00007ffff73e4d90 in start_thread () from /lib64/libpthread.so.0
#35726 0x00007ffff5cf5f5d in clone () from /lib64/libc.so.6
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diff --git a/servers/slapd/overlays/memberof.c b/servers/slapd/overlays/memberof.c
index 502cb46..356c1e6 100644
--- a/servers/slapd/overlays/memberof.c
+++ b/servers/slapd/overlays/memberof.c
@@ -190,7 +190,16 @@ typedef struct memberof_cbinfo_t {
BerVarray memberof;
memberof_is_t what;
} memberof_cbinfo_t;
-
+
+static void
+memberof_set_backend(Operation *op_target, Operation *op, slap_overinst *on)
+{
+ BackendInfo *bi = op->o_bd->bd_info;
+
+ if (bi->bi_type == memberof.on_bi.bi_type)
+ op_target->o_bd->bd_info = (BackendInfo *)on->on_info;
+}
+
static int
memberof_isGroupOrMember_cb( Operation *op, SlapReply *rs )
{
@@ -285,7 +294,7 @@ memberof_isGroupOrMember( Operation *op, memberof_cbinfo_t *mci )
op2.ors_filterstr = mo->mo_groupFilterstr;
op2.ors_filter = &mo->mo_groupFilter;
- op2.o_bd->bd_info = (BackendInfo *)on->on_info;
+ memberof_set_backend(&op2, op, on);
(void)op->o_bd->be_search( &op2, &rs2 );
op2.o_bd->bd_info = bi;
@@ -307,7 +316,7 @@ memberof_isGroupOrMember( Operation *op, memberof_cbinfo_t *mci )
op2.ors_filterstr = mo->mo_memberFilterstr;
op2.ors_filter = &mo->mo_memberFilter;
- op2.o_bd->bd_info = (BackendInfo *)on->on_info;
+ memberof_set_backend(&op2, op, on);
(void)op->o_bd->be_search( &op2, &rs2 );
op2.o_bd->bd_info = bi;
@@ -407,7 +416,7 @@ memberof_value_modify(
oex.oe_key = (void *)&memberof;
LDAP_SLIST_INSERT_HEAD(&op2.o_extra, &oex, oe_next);
- op2.o_bd->bd_info = (BackendInfo *)on->on_info;
+ memberof_set_backend(&op2, op, on);
(void)op->o_bd->be_modify( &op2, &rs2 );
op2.o_bd->bd_info = bi;
LDAP_SLIST_REMOVE(&op2.o_extra, &oex, OpExtra, oe_next);
@@ -449,7 +458,7 @@ memberof_value_modify(
oex.oe_key = (void *)&memberof;
LDAP_SLIST_INSERT_HEAD(&op2.o_extra, &oex, oe_next);
- op2.o_bd->bd_info = (BackendInfo *)on->on_info;
+ memberof_set_backend(&op2, op, on);
(void)op->o_bd->be_modify( &op2, &rs2 );
op2.o_bd->bd_info = bi;
LDAP_SLIST_REMOVE(&op2.o_extra, &oex, OpExtra, oe_next);
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