Re: [PATCH] net: initialize local variables in net/ipv6/mcast.c and net/ipv4/igmp.c
From: Eric Dumazet <hidden>
Date: 2021-04-02 17:49:51
Also in:
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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.
quoted hunk ↗ jump to hunk
Reported-by: syzbot+001516d86dbe88862cec@syzkaller.appspotmail.com Signed-off-by: Phillip Potter <phil@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_modediff --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;