From 960dbb956d9f9cb05b719087faed53c88dc80956 Mon Sep 17 00:00:00 2001
From: Chrostoper Ertl <chertl@microsoft.com>
Date: Thu, 28 Nov 2019 16:33:59 +0000
Subject: [PATCH 06/11] fru: Fix buffer overflow vulnerabilities
Partial fix for CVE-2020-5208, see
https://github.com/ipmitool/ipmitool/security/advisories/GHSA-g659-9qxw-p7cp
The `read_fru_area_section` function only performs size validation of
requested read size, and falsely assumes that the IPMI message will not
respond with more than the requested amount of data; it uses the
unvalidated response size to copy into `frubuf`. If the response is
larger than the request, this can result in overflowing the buffer.
The same issue affects the `read_fru_area` function.
---
lib/ipmi_fru.c | 33 +++++++++++++++++++++++++++++++--
1 file changed, 31 insertions(+), 2 deletions(-)
--- a/lib/ipmi_fru.c
+++ b/lib/ipmi_fru.c
@@ -615,7 +615,10 @@ int
read_fru_area(struct ipmi_intf * intf, struct fru_info *fru, uint8_t id,
uint32_t offset, uint32_t length, uint8_t *frubuf)
{
- uint32_t off = offset, tmp, finish;
+ uint32_t off = offset;
+ uint32_t tmp;
+ uint32_t finish;
+ uint32_t size_left_in_buffer;
struct ipmi_rs * rsp;
struct ipmi_rq req;
uint8_t msg_data[4];
@@ -628,10 +631,12 @@ read_fru_area(struct ipmi_intf * intf, s
finish = offset + length;
if (finish > fru->size) {
+ memset(frubuf + fru->size, 0, length - fru->size);
finish = fru->size;
lprintf(LOG_NOTICE, "Read FRU Area length %d too large, "
"Adjusting to %d",
offset + length, finish - offset);
+ length = finish - offset;
}
memset(&req, 0, sizeof(req));
@@ -667,6 +672,7 @@ read_fru_area(struct ipmi_intf * intf, s
}
}
+ size_left_in_buffer = length;
do {
tmp = fru->access ? off >> 1 : off;
msg_data[0] = id;
@@ -707,9 +713,18 @@ read_fru_area(struct ipmi_intf * intf, s
}
tmp = fru->access ? rsp->data[0] << 1 : rsp->data[0];
+ if(rsp->data_len < 1
+ || tmp > rsp->data_len - 1
+ || tmp > size_left_in_buffer)
+ {
+ printf(" Not enough buffer size");
+ return -1;
+ }
+
memcpy(frubuf, rsp->data + 1, tmp);
off += tmp;
frubuf += tmp;
+ size_left_in_buffer -= tmp;
/* sometimes the size returned in the Info command
* is too large. return 0 so higher level function
* still attempts to parse what was returned */
@@ -742,7 +757,9 @@ read_fru_area_section(struct ipmi_intf *
uint32_t offset, uint32_t length, uint8_t *frubuf)
{
static uint32_t fru_data_rqst_size = 20;
- uint32_t off = offset, tmp, finish;
+ uint32_t off = offset;
+ uint32_t tmp, finish;
+ uint32_t size_left_in_buffer;
struct ipmi_rs * rsp;
struct ipmi_rq req;
uint8_t msg_data[4];
@@ -755,10 +772,12 @@ read_fru_area_section(struct ipmi_intf *
finish = offset + length;
if (finish > fru->size) {
+ memset(frubuf + fru->size, 0, length - fru->size);
finish = fru->size;
lprintf(LOG_NOTICE, "Read FRU Area length %d too large, "
"Adjusting to %d",
offset + length, finish - offset);
+ length = finish - offset;
}
memset(&req, 0, sizeof(req));
@@ -773,6 +792,8 @@ read_fru_area_section(struct ipmi_intf *
if (fru->access && fru_data_rqst_size > 16)
#endif
fru_data_rqst_size = 16;
+
+ size_left_in_buffer = length;
do {
tmp = fru->access ? off >> 1 : off;
msg_data[0] = id;
@@ -804,8 +825,16 @@ read_fru_area_section(struct ipmi_intf *
}
tmp = fru->access ? rsp->data[0] << 1 : rsp->data[0];
+ if(rsp->data_len < 1
+ || tmp > rsp->data_len - 1
+ || tmp > size_left_in_buffer)
+ {
+ printf(" Not enough buffer size");
+ return -1;
+ }
memcpy((frubuf + off)-offset, rsp->data + 1, tmp);
off += tmp;
+ size_left_in_buffer -= tmp;
/* sometimes the size returned in the Info command
* is too large. return 0 so higher level function