* [PATCH net] smc: fix out of bound access in smc_nl_get_sys_info()
@ 2020-12-30 0:48 Jakub Kicinski
2021-01-04 11:53 ` Karsten Graul
0 siblings, 1 reply; 2+ messages in thread
From: Jakub Kicinski @ 2020-12-30 0:48 UTC (permalink / raw)
To: davem
Cc: kgraul, guvenc, linux-s390, netdev, Jakub Kicinski,
syzbot+f4708c391121cfc58396
smc_clc_get_hostname() sets the host pointer to a buffer
which is not NULL-terminated (see smc_clc_init()).
Reported-by: syzbot+f4708c391121cfc58396@syzkaller.appspotmail.com
Fixes: 099b990bd11a ("net/smc: Add support for obtaining system information")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
net/smc/smc_core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 59342b519e34..8d866b4ed8f6 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -246,7 +246,8 @@ int smc_nl_get_sys_info(struct sk_buff *skb, struct netlink_callback *cb)
goto errattr;
smc_clc_get_hostname(&host);
if (host) {
- snprintf(hostname, sizeof(hostname), "%s", host);
+ memcpy(hostname, host, SMC_MAX_HOSTNAME_LEN);
+ hostname[SMC_MAX_HOSTNAME_LEN] = 0;
if (nla_put_string(skb, SMC_NLA_SYS_LOCAL_HOST, hostname))
goto errattr;
}
--
2.26.2
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH net] smc: fix out of bound access in smc_nl_get_sys_info()
2020-12-30 0:48 [PATCH net] smc: fix out of bound access in smc_nl_get_sys_info() Jakub Kicinski
@ 2021-01-04 11:53 ` Karsten Graul
0 siblings, 0 replies; 2+ messages in thread
From: Karsten Graul @ 2021-01-04 11:53 UTC (permalink / raw)
To: Jakub Kicinski, davem
Cc: guvenc, linux-s390, netdev, syzbot+f4708c391121cfc58396
Thank you Jakub,
this patch solves the out of bounds access due to snprintf() copying size bytes first
and overwriting the last byte with null afterwards.
We will include your patch in our next series for the net tree soon.
Reviewed-by: Karsten Graul <kgraul@linux.ibm.com>
On 30/12/2020 01:48, Jakub Kicinski wrote:
> smc_clc_get_hostname() sets the host pointer to a buffer
> which is not NULL-terminated (see smc_clc_init()).
>
> Reported-by: syzbot+f4708c391121cfc58396@syzkaller.appspotmail.com
> Fixes: 099b990bd11a ("net/smc: Add support for obtaining system information")
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
> net/smc/smc_core.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
> index 59342b519e34..8d866b4ed8f6 100644
> --- a/net/smc/smc_core.c
> +++ b/net/smc/smc_core.c
> @@ -246,7 +246,8 @@ int smc_nl_get_sys_info(struct sk_buff *skb, struct netlink_callback *cb)
> goto errattr;
> smc_clc_get_hostname(&host);
> if (host) {
> - snprintf(hostname, sizeof(hostname), "%s", host);
> + memcpy(hostname, host, SMC_MAX_HOSTNAME_LEN);
> + hostname[SMC_MAX_HOSTNAME_LEN] = 0;
> if (nla_put_string(skb, SMC_NLA_SYS_LOCAL_HOST, hostname))
> goto errattr;
> }
>
--
Karsten
(I'm a dude)
^ permalink raw reply [flat|nested] 2+ messages in thread
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