<p>Harald Welte <strong>merged</strong> this change.</p><p><a href="https://gerrit.osmocom.org/10578">View Change</a></p><div style="white-space:pre-wrap">Approvals:
Harald Welte: Looks good to me, approved
Jenkins Builder: Verified
</div><pre style="font-family: monospace,monospace; white-space: pre-wrap;">Fix heap-use-after-free due to OML link destruction<br><br>ipaccess_drop_oml was being called inside an osmo_fd cb context, were<br>-EBADF must be returned if the structure holding the osmo_fd is freed.<br>In the middle of the path (see OS#3495 for path tree) it goes through a<br>signal dispatch, so it's impossible to make sure we return some value to<br>the osmo_fd cb. As a result, it is required to defer dropping the OML<br>Link from current code path and do it through a timer.<br><br>Fixes following ASan report:<br>20180822124927913 <0004> abis_nm.c:787 OC=RADIO-CARRIER(02) INST=(00,00,ff): CHANGE ADMINISTRATIVE STATE NACK CAUSE=Message cannot be performed<br>20180822124927913 <0004> osmo_bsc_main.c:186 Got CHANGE ADMINISTRATIVE STATE NACK going to drop the OML links.<br>20180822124927913 <0015> bts_ipaccess_nanobts.c:406 (bts=0) Dropping OML link.<br>...<br>=================================================================<br>==17607==ERROR: AddressSanitizer: heap-use-after-free on address 0x62e000060a68 at pc 0x7f5ea8e27086 bp 0x7ffde92b6d80 sp 0x7ffde92b6d78<br>READ of size 8 at 0x62e000060a68 thread T0<br> #0 0x7f5ea8e27085 in handle_ts1_write input/ipaccess.c:371<br> #1 0x7f5ea8e27085 in ipaccess_fd_cb input/ipaccess.c:391<br> #2 0x7f5ea9147ca8 in osmo_fd_disp_fds libosmocore/src/select.c:217<br> #3 0x7f5ea9147ca8 in osmo_select_main libosmocore/src/select.c:257<br> #4 0x555813ab79d6 in main osmo-bsc/osmo_bsc_main.c:922<br> #5 0x7f5ea76d02e0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202e0)<br> #6 0x555813ab84e9 in _start (/bin/osmo-bsc+0x34d4e9)<br><br>Fixes: OS#3495<br>Change-Id: I7c794c763481c28e8c35dc9b11d27969e16feb3c<br>---<br>M include/osmocom/bsc/gsm_data.h<br>M include/osmocom/bsc/ipaccess.h<br>M src/osmo-bsc/bts_ipaccess_nanobts.c<br>M src/osmo-bsc/osmo_bsc_main.c<br>4 files changed, 31 insertions(+), 2 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h</span><br><span>index f85887a..b827d0a 100644</span><br><span>--- a/include/osmocom/bsc/gsm_data.h</span><br><span>+++ b/include/osmocom/bsc/gsm_data.h</span><br><span>@@ -923,6 +923,8 @@</span><br><span> struct gsm_e1_subslot oml_e1_link;</span><br><span> uint8_t oml_tei;</span><br><span> struct e1inp_sign_link *oml_link;</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Timer to use for deferred drop of OML link, see \ref ipaccess_drop_oml_deferred */</span><br><span style="color: hsl(120, 100%, 40%);">+ struct osmo_timer_list oml_drop_link_timer;</span><br><span> /* when OML link was established */</span><br><span> time_t uptime;</span><br><span> </span><br><span>diff --git a/include/osmocom/bsc/ipaccess.h b/include/osmocom/bsc/ipaccess.h</span><br><span>index 3d0f612..692e795 100644</span><br><span>--- a/include/osmocom/bsc/ipaccess.h</span><br><span>+++ b/include/osmocom/bsc/ipaccess.h</span><br><span>@@ -31,6 +31,7 @@</span><br><span> } __attribute__((packed));</span><br><span> </span><br><span> void ipaccess_drop_oml(struct gsm_bts *bts);</span><br><span style="color: hsl(120, 100%, 40%);">+void ipaccess_drop_oml_deferred(struct gsm_bts *bts);</span><br><span> void ipaccess_drop_rsl(struct gsm_bts_trx *trx);</span><br><span> </span><br><span> struct sdp_header_item {</span><br><span>diff --git a/src/osmo-bsc/bts_ipaccess_nanobts.c b/src/osmo-bsc/bts_ipaccess_nanobts.c</span><br><span>index 80f7c9c..fec4147 100644</span><br><span>--- a/src/osmo-bsc/bts_ipaccess_nanobts.c</span><br><span>+++ b/src/osmo-bsc/bts_ipaccess_nanobts.c</span><br><span>@@ -166,7 +166,7 @@</span><br><span> enum abis_nm_chan_comb ccomb =</span><br><span> abis_nm_chcomb4pchan(ts->pchan_from_config);</span><br><span> if (abis_nm_set_channel_attr(ts, ccomb) == -EINVAL) {</span><br><span style="color: hsl(0, 100%, 40%);">- ipaccess_drop_oml(trx->bts);</span><br><span style="color: hsl(120, 100%, 40%);">+ ipaccess_drop_oml_deferred(trx->bts);</span><br><span> return -1;</span><br><span> }</span><br><span> abis_nm_chg_adm_state(trx->bts, obj_class,</span><br><span>@@ -400,6 +400,9 @@</span><br><span> struct gsm_bts *rdep_bts;</span><br><span> struct gsm_bts_trx *trx;</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ /* First of all, remove deferred drop if enabled */</span><br><span style="color: hsl(120, 100%, 40%);">+ osmo_timer_del(&bts->oml_drop_link_timer);</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> if (!bts->oml_link)</span><br><span> return;</span><br><span> </span><br><span>@@ -432,6 +435,29 @@</span><br><span> }</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+/*! Callback for \ref ipaccess_drop_oml_deferred_cb.</span><br><span style="color: hsl(120, 100%, 40%);">+ */</span><br><span style="color: hsl(120, 100%, 40%);">+static void ipaccess_drop_oml_deferred_cb(void *data)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ struct gsm_bts *bts = (struct gsm_bts *) data;</span><br><span style="color: hsl(120, 100%, 40%);">+ ipaccess_drop_oml(bts);</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+/*! Deferr \ref ipacces_drop_oml through a timer to avoid dropping structures in</span><br><span style="color: hsl(120, 100%, 40%);">+ * current code context. This may be needed if we want to destroy the OML link</span><br><span style="color: hsl(120, 100%, 40%);">+ * while being called from a lower layer "struct osmo_fd" cb, were it is</span><br><span style="color: hsl(120, 100%, 40%);">+ * mandatory to return -EBADF if the osmo_fd has been destroyed. In case code</span><br><span style="color: hsl(120, 100%, 40%);">+ * destroying an OML link is called through an osmo_signal, it becomes</span><br><span style="color: hsl(120, 100%, 40%);">+ * impossible to return any value, thus deferring the destruction is required.</span><br><span style="color: hsl(120, 100%, 40%);">+ */</span><br><span style="color: hsl(120, 100%, 40%);">+void ipaccess_drop_oml_deferred(struct gsm_bts *bts)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ if (!osmo_timer_pending(&bts->oml_drop_link_timer) && bts->oml_link) {</span><br><span style="color: hsl(120, 100%, 40%);">+ LOGP(DLINP, LOGL_NOTICE, "(bts=%d) Deferring Drop of OML link.\n", bts->nr);</span><br><span style="color: hsl(120, 100%, 40%);">+ osmo_timer_setup(&bts->oml_drop_link_timer, ipaccess_drop_oml_deferred_cb, bts);</span><br><span style="color: hsl(120, 100%, 40%);">+ osmo_timer_schedule(&bts->oml_drop_link_timer, 0, 0);</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> /* This function is called once the OML/RSL link becomes up. */</span><br><span> static struct e1inp_sign_link *</span><br><span> ipaccess_sign_link_up(void *unit_data, struct e1inp_line *line,</span><br><span>diff --git a/src/osmo-bsc/osmo_bsc_main.c b/src/osmo-bsc/osmo_bsc_main.c</span><br><span>index 8ff0e8a..0dbe81c 100644</span><br><span>--- a/src/osmo-bsc/osmo_bsc_main.c</span><br><span>+++ b/src/osmo-bsc/osmo_bsc_main.c</span><br><span>@@ -191,7 +191,7 @@</span><br><span> }</span><br><span> </span><br><span> if (is_ipaccess_bts(nack->bts))</span><br><span style="color: hsl(0, 100%, 40%);">- ipaccess_drop_oml(nack->bts);</span><br><span style="color: hsl(120, 100%, 40%);">+ ipaccess_drop_oml_deferred(nack->bts);</span><br><span> </span><br><span> return 0;</span><br><span> }</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/10578">change 10578</a>. 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<div style="display:none"> Gerrit-Project: osmo-bsc </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-MessageType: merged </div>
<div style="display:none"> Gerrit-Change-Id: I7c794c763481c28e8c35dc9b11d27969e16feb3c </div>
<div style="display:none"> Gerrit-Change-Number: 10578 </div>
<div style="display:none"> Gerrit-PatchSet: 2 </div>
<div style="display:none"> Gerrit-Owner: Pau Espin Pedrol <pespin@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: Harald Welte <laforge@gnumonks.org> </div>
<div style="display:none"> Gerrit-Reviewer: Jenkins Builder (1000002) </div>