<p>laforge <strong>submitted</strong> this change.</p><p><a href="https://gerrit.osmocom.org/c/libosmo-sccp/+/16771">View Change</a></p><div style="white-space:pre-wrap">Approvals:
Jenkins Builder: Verified
laforge: Looks good to me, approved
</div><pre style="font-family: monospace,monospace; white-space: pre-wrap;">sua.c: Avoid double free in sua_rx_msg()->...->mtp_user_prim_cb()<br><br>Old commit of mine successfully fixed a memory leak, but apparently<br>after some more investigation it seems to have introduced a double free<br>of xua object in other code paths.<br><br>Nowadays, it seems scrc_rx_mtp_xfer_ind_xua() is called from 3 different places:<br>mtp_user_prim_cb()<br>sua_rx_cl()<br>sua_rx_co()<br><br>Before present patch, first caller is not freeing the xua message and my<br>old commit made scrc_rx_mtp_xfer_ind_xua() free it (by passing<br>ownsership of the object). But the other 2 callers do free the xua<br>object afterwards (actually the grandparent caller sua_rx_msg() does<br>it), which means it would double-free the xua object.<br><br>Let's move ownership out of scrc_rx_mtp_xfer_ind_xua() and let the<br>caller free the xua object (only changes need on the first caller). This<br>way everybody is happy and we keep the free() closer to the alloc().<br><br>Change-Id: Ia550b781b97adbdc0a0ad58a1075e5467e056f1e<br>Related: OS#4348<br>Fixes: 9c3baa89fb6b3fc1ef588930f361d013f98a1e39<br>---<br>M src/sccp_scrc.c<br>M src/sccp_user.c<br>2 files changed, 5 insertions(+), 12 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/src/sccp_scrc.c b/src/sccp_scrc.c</span><br><span>index db49299..e259d7c 100644</span><br><span>--- a/src/sccp_scrc.c</span><br><span>+++ b/src/sccp_scrc.c</span><br><span>@@ -438,14 +438,13 @@</span><br><span> }</span><br><span> </span><br><span> /* Figure C.1/Q.714 Sheet 1 of 12, after we converted the</span><br><span style="color: hsl(0, 100%, 40%);">- * MTP-TRANSFER.ind to SUA. Takes ownership of \a xua and frees it once processed. */</span><br><span style="color: hsl(120, 100%, 40%);">+ * MTP-TRANSFER.ind to SUA. */</span><br><span> int scrc_rx_mtp_xfer_ind_xua(struct osmo_sccp_instance *inst,</span><br><span> struct xua_msg *xua)</span><br><span> {</span><br><span> struct osmo_sccp_addr called;</span><br><span> uint32_t proto_class;</span><br><span> struct xua_msg_part *hop_ctr_part;</span><br><span style="color: hsl(0, 100%, 40%);">- int rc;</span><br><span> </span><br><span> LOGP(DLSS7, LOGL_DEBUG, "%s: %s\n", __func__, xua_msg_dump(xua, &xua_dialect_sua));</span><br><span> /* TODO: SCCP or nodal congestion? */</span><br><span>@@ -455,7 +454,6 @@</span><br><span> /* Node 1 (Sheet 3) */</span><br><span> /* deliver to SCOC */</span><br><span> sccp_scoc_rx_from_scrc(inst, xua);</span><br><span style="color: hsl(0, 100%, 40%);">- xua_msg_free(xua);</span><br><span> return 0;</span><br><span> }</span><br><span> /* We only treat connectionless and CR below */</span><br><span>@@ -465,9 +463,7 @@</span><br><span> /* Route on GT? */</span><br><span> if (called.ri != OSMO_SCCP_RI_GT) {</span><br><span> /* Node 6 (Sheet 3) */</span><br><span style="color: hsl(0, 100%, 40%);">- rc = scrc_node_6(inst, xua, &called);</span><br><span style="color: hsl(0, 100%, 40%);">- xua_msg_free(xua);</span><br><span style="color: hsl(0, 100%, 40%);">- return rc;</span><br><span style="color: hsl(120, 100%, 40%);">+ return scrc_node_6(inst, xua, &called);</span><br><span> }</span><br><span> /* Message with hop-counter? */</span><br><span> hop_ctr_part = xua_msg_find_tag(xua, SUA_IEI_S7_HOP_CTR);</span><br><span>@@ -476,9 +472,7 @@</span><br><span> if (hop_counter <= 1) {</span><br><span> /* Error: hop-counter violation */</span><br><span> /* node 4 */</span><br><span style="color: hsl(0, 100%, 40%);">- rc = scrc_node_4(inst, xua, SCCP_RETURN_CAUSE_HOP_COUNTER_VIOLATION);</span><br><span style="color: hsl(0, 100%, 40%);">- xua_msg_free(xua);</span><br><span style="color: hsl(0, 100%, 40%);">- return rc;</span><br><span style="color: hsl(120, 100%, 40%);">+ return scrc_node_4(inst, xua, SCCP_RETURN_CAUSE_HOP_COUNTER_VIOLATION);</span><br><span> }</span><br><span> /* Decrement hop-counter */</span><br><span> hop_counter--;</span><br><span>@@ -498,7 +492,5 @@</span><br><span> default:</span><br><span> break;</span><br><span> }</span><br><span style="color: hsl(0, 100%, 40%);">- rc = scrc_translate_node_9(inst, xua, &called);</span><br><span style="color: hsl(0, 100%, 40%);">- xua_msg_free(xua);</span><br><span style="color: hsl(0, 100%, 40%);">- return rc;</span><br><span style="color: hsl(120, 100%, 40%);">+ return scrc_translate_node_9(inst, xua, &called);</span><br><span> }</span><br><span>diff --git a/src/sccp_user.c b/src/sccp_user.c</span><br><span>index 929445f..49cc212 100644</span><br><span>--- a/src/sccp_user.c</span><br><span>+++ b/src/sccp_user.c</span><br><span>@@ -174,6 +174,7 @@</span><br><span> xua->mtp = omp->u.transfer;</span><br><span> /* hand this primitive into SCCP via the SCRC code */</span><br><span> rc = scrc_rx_mtp_xfer_ind_xua(inst, xua);</span><br><span style="color: hsl(120, 100%, 40%);">+ xua_msg_free(xua);</span><br><span> break;</span><br><span> default:</span><br><span> LOGP(DLSCCP, LOGL_ERROR, "Unknown primitive %u:%u receivd\n",</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/c/libosmo-sccp/+/16771">change 16771</a>. 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<div style="display:none"> Gerrit-Project: libosmo-sccp </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-Change-Id: Ia550b781b97adbdc0a0ad58a1075e5467e056f1e </div>
<div style="display:none"> Gerrit-Change-Number: 16771 </div>
<div style="display:none"> Gerrit-PatchSet: 1 </div>
<div style="display:none"> Gerrit-Owner: pespin <pespin@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: Jenkins Builder </div>
<div style="display:none"> Gerrit-Reviewer: laforge <laforge@osmocom.org> </div>
<div style="display:none"> Gerrit-MessageType: merged </div>