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Harald Welte gerrit-no-reply at lists.osmocom.orgHarald Welte has submitted this change and it was merged. ( https://gerrit.osmocom.org/10578 ) Change subject: Fix heap-use-after-free due to OML link destruction ...................................................................... Fix heap-use-after-free due to OML link destruction ipaccess_drop_oml was being called inside an osmo_fd cb context, were -EBADF must be returned if the structure holding the osmo_fd is freed. In the middle of the path (see OS#3495 for path tree) it goes through a signal dispatch, so it's impossible to make sure we return some value to the osmo_fd cb. As a result, it is required to defer dropping the OML Link from current code path and do it through a timer. Fixes following ASan report: 20180822124927913 <0004> abis_nm.c:787 OC=RADIO-CARRIER(02) INST=(00,00,ff): CHANGE ADMINISTRATIVE STATE NACK CAUSE=Message cannot be performed 20180822124927913 <0004> osmo_bsc_main.c:186 Got CHANGE ADMINISTRATIVE STATE NACK going to drop the OML links. 20180822124927913 <0015> bts_ipaccess_nanobts.c:406 (bts=0) Dropping OML link. ... ================================================================= ==17607==ERROR: AddressSanitizer: heap-use-after-free on address 0x62e000060a68 at pc 0x7f5ea8e27086 bp 0x7ffde92b6d80 sp 0x7ffde92b6d78 READ of size 8 at 0x62e000060a68 thread T0 #0 0x7f5ea8e27085 in handle_ts1_write input/ipaccess.c:371 #1 0x7f5ea8e27085 in ipaccess_fd_cb input/ipaccess.c:391 #2 0x7f5ea9147ca8 in osmo_fd_disp_fds libosmocore/src/select.c:217 #3 0x7f5ea9147ca8 in osmo_select_main libosmocore/src/select.c:257 #4 0x555813ab79d6 in main osmo-bsc/osmo_bsc_main.c:922 #5 0x7f5ea76d02e0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202e0) #6 0x555813ab84e9 in _start (/bin/osmo-bsc+0x34d4e9) Fixes: OS#3495 Change-Id: I7c794c763481c28e8c35dc9b11d27969e16feb3c --- M include/osmocom/bsc/gsm_data.h M include/osmocom/bsc/ipaccess.h M src/osmo-bsc/bts_ipaccess_nanobts.c M src/osmo-bsc/osmo_bsc_main.c 4 files changed, 31 insertions(+), 2 deletions(-) Approvals: Harald Welte: Looks good to me, approved Jenkins Builder: Verified diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h index f85887a..b827d0a 100644 --- a/include/osmocom/bsc/gsm_data.h +++ b/include/osmocom/bsc/gsm_data.h @@ -923,6 +923,8 @@ struct gsm_e1_subslot oml_e1_link; uint8_t oml_tei; struct e1inp_sign_link *oml_link; + /* Timer to use for deferred drop of OML link, see \ref ipaccess_drop_oml_deferred */ + struct osmo_timer_list oml_drop_link_timer; /* when OML link was established */ time_t uptime; diff --git a/include/osmocom/bsc/ipaccess.h b/include/osmocom/bsc/ipaccess.h index 3d0f612..692e795 100644 --- a/include/osmocom/bsc/ipaccess.h +++ b/include/osmocom/bsc/ipaccess.h @@ -31,6 +31,7 @@ } __attribute__((packed)); void ipaccess_drop_oml(struct gsm_bts *bts); +void ipaccess_drop_oml_deferred(struct gsm_bts *bts); void ipaccess_drop_rsl(struct gsm_bts_trx *trx); struct sdp_header_item { diff --git a/src/osmo-bsc/bts_ipaccess_nanobts.c b/src/osmo-bsc/bts_ipaccess_nanobts.c index 80f7c9c..fec4147 100644 --- a/src/osmo-bsc/bts_ipaccess_nanobts.c +++ b/src/osmo-bsc/bts_ipaccess_nanobts.c @@ -166,7 +166,7 @@ enum abis_nm_chan_comb ccomb = abis_nm_chcomb4pchan(ts->pchan_from_config); if (abis_nm_set_channel_attr(ts, ccomb) == -EINVAL) { - ipaccess_drop_oml(trx->bts); + ipaccess_drop_oml_deferred(trx->bts); return -1; } abis_nm_chg_adm_state(trx->bts, obj_class, @@ -400,6 +400,9 @@ struct gsm_bts *rdep_bts; struct gsm_bts_trx *trx; + /* First of all, remove deferred drop if enabled */ + osmo_timer_del(&bts->oml_drop_link_timer); + if (!bts->oml_link) return; @@ -432,6 +435,29 @@ } } +/*! Callback for \ref ipaccess_drop_oml_deferred_cb. + */ +static void ipaccess_drop_oml_deferred_cb(void *data) +{ + struct gsm_bts *bts = (struct gsm_bts *) data; + ipaccess_drop_oml(bts); +} +/*! Deferr \ref ipacces_drop_oml through a timer to avoid dropping structures in + * current code context. This may be needed if we want to destroy the OML link + * while being called from a lower layer "struct osmo_fd" cb, were it is + * mandatory to return -EBADF if the osmo_fd has been destroyed. In case code + * destroying an OML link is called through an osmo_signal, it becomes + * impossible to return any value, thus deferring the destruction is required. + */ +void ipaccess_drop_oml_deferred(struct gsm_bts *bts) +{ + if (!osmo_timer_pending(&bts->oml_drop_link_timer) && bts->oml_link) { + LOGP(DLINP, LOGL_NOTICE, "(bts=%d) Deferring Drop of OML link.\n", bts->nr); + osmo_timer_setup(&bts->oml_drop_link_timer, ipaccess_drop_oml_deferred_cb, bts); + osmo_timer_schedule(&bts->oml_drop_link_timer, 0, 0); + } +} + /* This function is called once the OML/RSL link becomes up. */ static struct e1inp_sign_link * ipaccess_sign_link_up(void *unit_data, struct e1inp_line *line, diff --git a/src/osmo-bsc/osmo_bsc_main.c b/src/osmo-bsc/osmo_bsc_main.c index 8ff0e8a..0dbe81c 100644 --- a/src/osmo-bsc/osmo_bsc_main.c +++ b/src/osmo-bsc/osmo_bsc_main.c @@ -191,7 +191,7 @@ } if (is_ipaccess_bts(nack->bts)) - ipaccess_drop_oml(nack->bts); + ipaccess_drop_oml_deferred(nack->bts); return 0; } -- To view, visit https://gerrit.osmocom.org/10578 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-bsc Gerrit-Branch: master Gerrit-MessageType: merged Gerrit-Change-Id: I7c794c763481c28e8c35dc9b11d27969e16feb3c Gerrit-Change-Number: 10578 Gerrit-PatchSet: 2 Gerrit-Owner: Pau Espin Pedrol <pespin at sysmocom.de> Gerrit-Reviewer: Harald Welte <laforge at gnumonks.org> Gerrit-Reviewer: Jenkins Builder (1000002) -------------- next part -------------- An HTML attachment was scrubbed... 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