From 98b47424cf548f58c4d295fa8235210406ea85ca Mon Sep 17 00:00:00 2001 From: Chrostoper Ertl Date: Thu, 28 Nov 2019 17:13:45 +0000 Subject: [PATCH 11/11] fru, sdr: Fix id_string buffer overflows Final part of the fixes for CVE-2020-5208, see https://github.com/ipmitool/ipmitool/security/advisories/GHSA-g659-9qxw-p7cp 9 variants of stack buffer overflow when parsing `id_string` field of SDR records returned from `CMD_GET_SDR` command. SDR record structs have an `id_code` field, and an `id_string` `char` array. The length of `id_string` is calculated as `(id_code & 0x1f) + 1`, which can be larger than expected 16 characters (if `id_code = 0xff`, then length will be `(0xff & 0x1f) + 1 = 32`). In numerous places, this can cause stack buffer overflow when copying into fixed buffer of size `17` bytes from this calculated length. --- lib/ipmi_fru.c | 2 +- lib/ipmi_sdr.c | 40 ++++++++++++++++++++++++---------------- 2 files changed, 25 insertions(+), 17 deletions(-) --- a/lib/ipmi_fru.c +++ b/lib/ipmi_fru.c @@ -3062,7 +3062,7 @@ ipmi_fru_print(struct ipmi_intf * intf, return 0; memset(desc, 0, sizeof(desc)); - memcpy(desc, fru->id_string, fru->id_code & 0x01f); + memcpy(desc, fru->id_string, __min(fru->id_code & 0x01f, sizeof(desc))); desc[fru->id_code & 0x01f] = 0; printf("FRU Device Description : %s (ID %d)\n", desc, fru->device_id); --- a/lib/ipmi_sdr.c +++ b/lib/ipmi_sdr.c @@ -2084,7 +2084,7 @@ ipmi_sdr_print_sensor_eventonly(struct i return -1; memset(desc, 0, sizeof (desc)); - snprintf(desc, (sensor->id_code & 0x1f) + 1, "%s", sensor->id_string); + snprintf(desc, sizeof(desc), "%.*s", (sensor->id_code & 0x1f) + 1, sensor->id_string); if (verbose) { printf("Sensor ID : %s (0x%x)\n", @@ -2135,7 +2135,7 @@ ipmi_sdr_print_sensor_mc_locator(struct return -1; memset(desc, 0, sizeof (desc)); - snprintf(desc, (mc->id_code & 0x1f) + 1, "%s", mc->id_string); + snprintf(desc, sizeof(desc), "%.*s", (mc->id_code & 0x1f) + 1, mc->id_string); if (verbose == 0) { if (csv_output) @@ -2228,7 +2228,7 @@ ipmi_sdr_print_sensor_generic_locator(st char desc[17]; memset(desc, 0, sizeof (desc)); - snprintf(desc, (dev->id_code & 0x1f) + 1, "%s", dev->id_string); + snprintf(desc, sizeof(desc), "%.*s", (dev->id_code & 0x1f) + 1, dev->id_string); if (!verbose) { if (csv_output) @@ -2285,7 +2285,7 @@ ipmi_sdr_print_sensor_fru_locator(struct char desc[17]; memset(desc, 0, sizeof (desc)); - snprintf(desc, (fru->id_code & 0x1f) + 1, "%s", fru->id_string); + snprintf(desc, sizeof(desc), "%.*s", (fru->id_code & 0x1f) + 1, fru->id_string); if (!verbose) { if (csv_output) @@ -2489,35 +2489,43 @@ ipmi_sdr_print_name_from_rawentry(struct int rc =0; char desc[17]; + const char *id_string; + uint8_t id_code; memset(desc, ' ', sizeof (desc)); switch ( type) { case SDR_RECORD_TYPE_FULL_SENSOR: record.full = (struct sdr_record_full_sensor *) raw; - snprintf(desc, (record.full->id_code & 0x1f) +1, "%s", - (const char *)record.full->id_string); + id_code = record.full->id_code; + id_string = record.full->id_string; break; + case SDR_RECORD_TYPE_COMPACT_SENSOR: record.compact = (struct sdr_record_compact_sensor *) raw ; - snprintf(desc, (record.compact->id_code & 0x1f) +1, "%s", - (const char *)record.compact->id_string); + id_code = record.compact->id_code; + id_string = record.compact->id_string; break; + case SDR_RECORD_TYPE_EVENTONLY_SENSOR: record.eventonly = (struct sdr_record_eventonly_sensor *) raw ; - snprintf(desc, (record.eventonly->id_code & 0x1f) +1, "%s", - (const char *)record.eventonly->id_string); - break; + id_code = record.eventonly->id_code; + id_string = record.eventonly->id_string; + break; + case SDR_RECORD_TYPE_MC_DEVICE_LOCATOR: record.mcloc = (struct sdr_record_mc_locator *) raw ; - snprintf(desc, (record.mcloc->id_code & 0x1f) +1, "%s", - (const char *)record.mcloc->id_string); + id_code = record.mcloc->id_code; + id_string = record.mcloc->id_string; break; + default: rc = -1; - break; - } + } + if (!rc) { + snprintf(desc, sizeof(desc), "%.*s", (id_code & 0x1f) + 1, id_string); + } - lprintf(LOG_INFO, "ID: 0x%04x , NAME: %-16s", id, desc); + lprintf(LOG_INFO, "ID: 0x%04x , NAME: %-16s", id, desc); return rc; }