When receiving proposal msg in server, the field smcd_v2_ext_offset in
proposal msg is from the remote client and can not be fully trusted.
Once the value of smcd_v2_ext_offset exceed the max value, there has
the chance to access wrong address, and crash may happen.
This patch checks the value of smcd_v2_ext_offset before using it.
Fixes: 5c21c4ccafe8 ("net/smc: determine accepted ISM devices")
Signed-off-by: Guangguan Wang <guangguan.wang@xxxxxxxxxxxxxxxxx>
Reviewed-by: Wen Gu <guwen@xxxxxxxxxxxxxxxxx>
Reviewed-by: D. Wythe <alibuda@xxxxxxxxxxxxxxxxx>
---
net/smc/af_smc.c | 2 ++
net/smc/smc_clc.h | 8 +++++++-
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 5bfd38eaee3a..ef4e0ff6beed 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -2147,6 +2147,8 @@ static void smc_find_ism_v2_device_serv(struct smc_sock *new_smc,
pclc_smcd = smc_get_clc_msg_smcd(pclc);
smc_v2_ext = smc_get_clc_v2_ext(pclc);
smcd_v2_ext = smc_get_clc_smcd_v2_ext(smc_v2_ext);
+ if (!pclc_smcd || !smc_v2_ext || !smcd_v2_ext)
+ goto not_found;
mutex_lock(&smcd_dev_list.mutex);
if (pclc_smcd->ism.chid) {
diff --git a/net/smc/smc_clc.h b/net/smc/smc_clc.h
index 23afa4df862e..767289925410 100644
--- a/net/smc/smc_clc.h
+++ b/net/smc/smc_clc.h
@@ -400,9 +400,15 @@ smc_get_clc_v2_ext(struct smc_clc_msg_proposal *prop)
static inline struct smc_clc_smcd_v2_extension *
smc_get_clc_smcd_v2_ext(struct smc_clc_v2_extension *prop_v2ext)
{
+ u16 max_offset = offsetof(struct smc_clc_msg_proposal_area, pclc_smcd_v2_ext) -
+ offsetof(struct smc_clc_msg_proposal_area, pclc_v2_ext) -
+ offsetof(struct smc_clc_v2_extension, hdr) -
+ offsetofend(struct smc_clnt_opts_area_hdr, smcd_v2_ext_offset);
+
if (!prop_v2ext)
return NULL;
- if (!ntohs(prop_v2ext->hdr.smcd_v2_ext_offset))
+ if (!ntohs(prop_v2ext->hdr.smcd_v2_ext_offset) ||
+ ntohs(prop_v2ext->hdr.smcd_v2_ext_offset) > max_offset)
return NULL;
return (struct smc_clc_smcd_v2_extension *)
--
2.24.3 (Apple Git-128)
