2022-04-01 20:11:22

by baihaowen

Subject: [PATCH] net/ipv4: fix potential NULL dereference in sisfb_post_sis300()

psin and psl could be null without checking null and return, so
we need to dereference after checking.

Signed-off-by: Haowen Bai <[email protected]>
---
net/ipv4/igmp.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 2ad3c7b..d400080 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -2569,7 +2569,7 @@ int ip_mc_msfget(struct sock *sk, struct ip_msfilter *msf,
copy_to_user(optval, msf, IP_MSFILTER_SIZE(0))) {
return -EFAULT;
}
- if (len &&
+ if (len && psl &&
copy_to_user(&optval->imsf_slist_flex[0], psl->sl_addr, len))
return -EFAULT;
return 0;
@@ -2608,7 +2608,7 @@ int ip_mc_gsfget(struct sock *sk, struct group_filter *gsf,
count = psl ? psl->sl_count : 0;
copycount = count < gsf->gf_numsrc ? count : gsf->gf_numsrc;
gsf->gf_numsrc = count;
- for (i = 0; i < copycount; i++, p++) {
+ for (i = 0; i < copycount && psin && psl; i++, p++) {
struct sockaddr_storage ss;

psin = (struct sockaddr_in *)&ss;
--
2.7.4

2022-04-04 23:53:25

by Eric Dumazet

Subject: Re: [PATCH] net/ipv4: fix potential NULL dereference in sisfb_post_sis300()

On 3/31/22 20:57, Haowen Bai wrote:
> psin and psl could be null without checking null and return, so
> we need to dereference after checking.
>
> Signed-off-by: Haowen Bai <[email protected]>
> ---
> net/ipv4/igmp.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
> index 2ad3c7b..d400080 100644
> --- a/net/ipv4/igmp.c
> +++ b/net/ipv4/igmp.c
> @@ -2569,7 +2569,7 @@ int ip_mc_msfget(struct sock *sk, struct ip_msfilter *msf,
> copy_to_user(optval, msf, IP_MSFILTER_SIZE(0))) {
> return -EFAULT;
> }
> - if (len &&
> + if (len && psl &&


len can not be !0 here if len was 0

psl = rtnl_dereference(pmc->sflist);

if (!psl) {

   count = 0;


->len == 0


> copy_to_user(&optval->imsf_slist_flex[0], psl->sl_addr, len))
> return -EFAULT;
> return 0;
> @@ -2608,7 +2608,7 @@ int ip_mc_gsfget(struct sock *sk, struct group_filter *gsf,
> count = psl ? psl->sl_count : 0;
> copycount = count < gsf->gf_numsrc ? count : gsf->gf_numsrc;
> gsf->gf_numsrc = count;
> - for (i = 0; i < copycount; i++, p++) {
> + for (i = 0; i < copycount && psin && psl; i++, p++) {
> struct sockaddr_storage ss;
>
> psin = (struct sockaddr_in *)&ss;


Same here.