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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 --nextPart2505210.xvcxic42sH Content-Disposition: attachment; filename="memberof_partial.patch" Content-Transfer-Encoding: 7Bit Content-Type: text/x-patch; charset="UTF-8"; name="memberof_partial.patch"
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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jvcelak＠redhat.com