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snmp: fix dangling pointer in snmp_traps #51

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merged 3 commits into from
Nov 29, 2024
Merged

snmp: fix dangling pointer in snmp_traps #51

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d274279
snmp: fix dangling pointer in snmp_traps
j123b567 Nov 1, 2024
55e4e2d
snmp: remove handling of varbind->prev because it is never used
j123b567 Nov 27, 2024
5f36247
snmp: remove unused prev field from snmp_varbind
j123b567 Nov 29, 2024
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1 change: 0 additions & 1 deletion src/apps/snmp/snmp_msg.c
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Original file line number Diff line number Diff line change
Expand Up @@ -328,7 +328,6 @@ snmp_receive(void *handle, struct pbuf *p, const ip_addr_t *source_ip, u16_t por
struct snmp_varbind vb;

vb.next = NULL;
vb.prev = NULL;
vb.type = SNMP_ASN1_TYPE_COUNTER32;
vb.value_len = sizeof(u32_t);

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14 changes: 1 addition & 13 deletions src/apps/snmp/snmp_traps.c
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Expand Up @@ -351,13 +351,11 @@ snmp_send_trap_or_notification_or_inform_generic(struct snmp_msg_trap *trap_msg,
u16_t tot_len = 0;
err_t err = ERR_OK;
u32_t timestamp = 0;
struct snmp_varbind *original_varbinds = varbinds;
struct snmp_varbind *original_prev = NULL;
struct snmp_obj_id snmp_trap_oid = { 0 }; /* used for converting SNMPv1 generic/specific trap parameter to SNMPv2 snmpTrapOID */
struct snmp_varbind snmp_v2_special_varbinds[] = {
/* First varbind is used to store sysUpTime */
{
NULL, /* *next */
NULL, /* *prev */
{ /* oid */
8, /* oid len */
{1, 3, 6, 1, 2, 1, 1, 3} /* oid for sysUpTime */
Expand All @@ -369,7 +367,6 @@ snmp_send_trap_or_notification_or_inform_generic(struct snmp_msg_trap *trap_msg,
/* Second varbind is used to store snmpTrapOID */
{
NULL, /* *next */
NULL, /* *prev */
{ /* oid */
10, /* oid len */
{1, 3, 6, 1, 6, 3, 1, 1, 4, 1} /* oid for snmpTrapOID */
Expand All @@ -383,23 +380,17 @@ snmp_send_trap_or_notification_or_inform_generic(struct snmp_msg_trap *trap_msg,
LWIP_ASSERT_SNMP_LOCKED();

snmp_v2_special_varbinds[0].next = &snmp_v2_special_varbinds[1];
snmp_v2_special_varbinds[1].prev = &snmp_v2_special_varbinds[0];

snmp_v2_special_varbinds[0].value = &timestamp;

snmp_v2_special_varbinds[1].next = varbinds;

/* see rfc3584 */
if (trap_msg->snmp_version == SNMP_VERSION_2c) {
struct snmp_obj_id snmp_trap_oid = { 0 }; /* used for converting SNMPv1 generic/specific trap parameter to SNMPv2 snmpTrapOID */
err = snmp_prepare_trap_oid(&snmp_trap_oid, eoid, generic_trap, specific_trap);
if (err == ERR_OK) {
snmp_v2_special_varbinds[1].value_len = snmp_trap_oid.len * sizeof(snmp_trap_oid.id[0]);
snmp_v2_special_varbinds[1].value = snmp_trap_oid.id;
if (varbinds != NULL) {
original_prev = varbinds->prev;
varbinds->prev = &snmp_v2_special_varbinds[1];
}
varbinds = snmp_v2_special_varbinds; /* After inserting two varbinds at the beginning of the list, make sure that pointer is pointing to the first element */
}
}
Expand All @@ -422,9 +413,6 @@ snmp_send_trap_or_notification_or_inform_generic(struct snmp_msg_trap *trap_msg,
}
}
}
if ((trap_msg->snmp_version == SNMP_VERSION_2c) && (original_varbinds != NULL)) {
original_varbinds->prev = original_prev;
}
req_id++;
return err;
}
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2 changes: 0 additions & 2 deletions src/include/lwip/apps/snmp.h
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Expand Up @@ -55,8 +55,6 @@ struct snmp_varbind
{
/** pointer to next varbind, NULL for last in list */
struct snmp_varbind *next;
/** pointer to previous varbind, NULL for first in list */
struct snmp_varbind *prev;

/** object identifier */
struct snmp_obj_id oid;
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