On 4/2/21 7:36 PM, Phillip Potter wrote:
> Use memset to initialize two local buffers in net/ipv6/mcast.c,
> and another in net/ipv4/igmp.c. Fixes a KMSAN found uninit-value
> bug reported by syzbot at:
> https://syzkaller.appspot.com/bug?id=0766d38c656abeace60621896d705743aeefed51
According to this link, the bug no longer triggers.
Please explain why you think it is still there.
>
> Reported-by: syzbot+001516d86dbe88862...@syzkaller.appspotmail.com
> Signed-off-by: Phillip Potter <p...@philpotter.co.uk>
> ---
> net/ipv4/igmp.c | 2 ++
> net/ipv6/mcast.c | 4 ++++
> 2 files changed, 6 insertions(+)
>
> diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
> index 7b272bbed2b4..bc8e358a9a2a 100644
> --- a/net/ipv4/igmp.c
> +++ b/net/ipv4/igmp.c
> @@ -1131,6 +1131,8 @@ static void ip_mc_filter_add(struct in_device *in_dev,
> __be32 addr)
> char buf[MAX_ADDR_LEN];
> struct net_device *dev = in_dev->dev;
>
> + memset(buf, 0, sizeof(buf));
> +
> /* Checking for IFF_MULTICAST here is WRONG-WRONG-WRONG.
> We will get multicast token leakage, when IFF_MULTICAST
> is changed. This check should be done in ndo_set_rx_mode
> diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
> index 6c8604390266..ad90dc28f318 100644
> --- a/net/ipv6/mcast.c
> +++ b/net/ipv6/mcast.c
> @@ -658,6 +658,8 @@ static void igmp6_group_added(struct ifmcaddr6 *mc)
> struct net_device *dev = mc->idev->dev;
> char buf[MAX_ADDR_LEN];
>
> + memset(buf, 0, sizeof(buf));
> +
> if (IPV6_ADDR_MC_SCOPE(&mc->mca_addr) <
> IPV6_ADDR_SCOPE_LINKLOCAL)
> return;
> @@ -694,6 +696,8 @@ static void igmp6_group_dropped(struct ifmcaddr6 *mc)
> struct net_device *dev = mc->idev->dev;
> char buf[MAX_ADDR_LEN];
>
> + memset(buf, 0, sizeof(buf));
> +
> if (IPV6_ADDR_MC_SCOPE(&mc->mca_addr) <
> IPV6_ADDR_SCOPE_LINKLOCAL)
> return;
>
