[oe] [PATCH][meta-networking] net-snmp: don't return incompletely parsed varbinds
rongqing.li at windriver.com
rongqing.li at windriver.com
Tue Jul 7 01:17:30 UTC 2015
From: Jian Liu <jian.liu at windriver.com>
the snmp_pdu_parse() function could leave incompletely parsed varBind
variables in the list of variables in case the parsing of the SNMP
PDU failed. If later processing tries to operate on the stale and
incompletely processed varBind (e.g. when printing the variables),
this can lead to e.g. crashes or, possibly, execution of arbitrary
code.
The snmp_pdu_parse() function stores varBind variables in a list of
netsnmp_variable_list structures. Each time the function parses a new
varBind, a new netsnmp_variable_list item is allocated on the heap
and linked to the list of variables. The problem is that this item
is not removed from the list, even if snmp_pdu_parse() fails to
complete the parsing.
The "type" member of the stale netsnmp_variable_list is not
properly initialized in case snmp_pdu_parse() returns early from the
parsing. However, the "type" member is used to determine later code
paths, which is why we see crashes in a variety of functions,
although the root cause for all of these is the same.
This patch come from
http://sourceforge.net/p/net-snmp/code/ci/f23bcd3ac6ddee5d0a48f9703007ccc738914791/
Written-by: Robert Story
Signed-off-by: Jian Liu <jian.liu at windriver.com>
---
...donnt-return-incompletely-parsed-varbinds.patch | 128 +++++++++++++++++++++
.../recipes-protocols/net-snmp/net-snmp_5.7.2.1.bb | 1 +
2 files changed, 129 insertions(+)
create mode 100644 meta-networking/recipes-protocols/net-snmp/net-snmp/donnt-return-incompletely-parsed-varbinds.patch
diff --git a/meta-networking/recipes-protocols/net-snmp/net-snmp/donnt-return-incompletely-parsed-varbinds.patch b/meta-networking/recipes-protocols/net-snmp/net-snmp/donnt-return-incompletely-parsed-varbinds.patch
new file mode 100644
index 0000000..04f2110
--- /dev/null
+++ b/meta-networking/recipes-protocols/net-snmp/net-snmp/donnt-return-incompletely-parsed-varbinds.patch
@@ -0,0 +1,128 @@
+the snmp_pdu_parse() function could leave
+incompletely parsed varBind variables in the list of variables in
+case the parsing of the SNMP PDU failed. If later processing tries to
+operate on the stale and incompletely processed varBind (e.g. when
+printing the variables), this can lead to e.g. crashes or, possibly,
+execution of arbitrary code
+
+Upstream-Status: Backport [net-snmp]
+
+Written-by: Robert Story
+
+diff -Nur net-snmp-5.7.2.1.orig/snmplib/snmp_api.c net-snmp-5.7.2.1/snmplib/snmp_api.c
+--- net-snmp-5.7.2.1.orig/snmplib/snmp_api.c 2015-05-27 11:25:11.563747471 +0800
++++ net-snmp-5.7.2.1/snmplib/snmp_api.c 2015-05-27 13:27:27.724748201 +0800
+@@ -4345,10 +4345,9 @@
+ u_char type;
+ u_char msg_type;
+ u_char *var_val;
+- int badtype = 0;
+ size_t len;
+ size_t four;
+- netsnmp_variable_list *vp = NULL;
++ netsnmp_variable_list *vp = NULL, *vplast = NULL;
+ oid objid[MAX_OID_LEN];
+
+ /*
+@@ -4487,38 +4486,24 @@
+ (ASN_SEQUENCE | ASN_CONSTRUCTOR),
+ "varbinds");
+ if (data == NULL)
+- return -1;
++ goto fail;
+
+ /*
+ * get each varBind sequence
+ */
+ while ((int) *length > 0) {
+- netsnmp_variable_list *vptemp;
+- vptemp = (netsnmp_variable_list *) malloc(sizeof(*vptemp));
+- if (NULL == vptemp) {
+- return -1;
+- }
+- if (NULL == vp) {
+- pdu->variables = vptemp;
+- } else {
+- vp->next_variable = vptemp;
+- }
+- vp = vptemp;
++ vp = SNMP_MALLOC_TYPEDEF(netsnmp_variable_list);
++ if (NULL == vp)
++ goto fail;
+
+- vp->next_variable = NULL;
+- vp->val.string = NULL;
+ vp->name_length = MAX_OID_LEN;
+- vp->name = NULL;
+- vp->index = 0;
+- vp->data = NULL;
+- vp->dataFreeHook = NULL;
+ DEBUGDUMPSECTION("recv", "VarBind");
+ data = snmp_parse_var_op(data, objid, &vp->name_length, &vp->type,
+ &vp->val_len, &var_val, length);
+ if (data == NULL)
+- return -1;
++ goto fail;
+ if (snmp_set_var_objid(vp, objid, vp->name_length))
+- return -1;
++ goto fail;
+
+ len = MAX_PACKET_LENGTH;
+ DEBUGDUMPHEADER("recv", "Value");
+@@ -4583,7 +4568,7 @@
+ vp->val.string = (u_char *) malloc(vp->val_len);
+ }
+ if (vp->val.string == NULL) {
+- return -1;
++ goto fail;
+ }
+ asn_parse_string(var_val, &len, &vp->type, vp->val.string,
+ &vp->val_len);
+@@ -4594,7 +4579,7 @@
+ vp->val_len *= sizeof(oid);
+ vp->val.objid = (oid *) malloc(vp->val_len);
+ if (vp->val.objid == NULL) {
+- return -1;
++ goto fail;
+ }
+ memmove(vp->val.objid, objid, vp->val_len);
+ break;
+@@ -4606,19 +4591,35 @@
+ case ASN_BIT_STR:
+ vp->val.bitstring = (u_char *) malloc(vp->val_len);
+ if (vp->val.bitstring == NULL) {
+- return -1;
++ goto fail;
+ }
+ asn_parse_bitstring(var_val, &len, &vp->type,
+ vp->val.bitstring, &vp->val_len);
+ break;
+ default:
+ snmp_log(LOG_ERR, "bad type returned (%x)\n", vp->type);
+- badtype = -1;
++ goto fail;
+ break;
+ }
+ DEBUGINDENTADD(-4);
++
++ if (NULL == vplast) {
++ pdu->variables = vp;
++ } else {
++ vplast->next_variable = vp;
++ }
++ vplast = vp;
++ vp = NULL;
+ }
+- return badtype;
++ return 0;
++
++ fail:
++ DEBUGMSGTL(("recv", "error while parsing VarBindList\n"));
++ /** if we were parsing a var, remove it from the pdu and free it */
++ if (vp)
++ snmp_free_var(vp);
++
++ return -1;
+ }
+
+ /*
diff --git a/meta-networking/recipes-protocols/net-snmp/net-snmp_5.7.2.1.bb b/meta-networking/recipes-protocols/net-snmp/net-snmp_5.7.2.1.bb
index 93d3a94..b1f777e 100644
--- a/meta-networking/recipes-protocols/net-snmp/net-snmp_5.7.2.1.bb
+++ b/meta-networking/recipes-protocols/net-snmp/net-snmp_5.7.2.1.bb
@@ -21,6 +21,7 @@ SRC_URI = "${SOURCEFORGE_MIRROR}/net-snmp/net-snmp-${PV}.zip \
file://net-snmp-testing-add-the-output-format-for-ptest.patch \
file://run-ptest \
file://0001-Fix-CVE-2014-2285.patch \
+ file://donnt-return-incompletely-parsed-varbinds.patch \
"
SRC_URI[md5sum] = "a2c83518648b0f2a5d378625e45c0e18"
--
1.9.1
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