From c3b704d4a4a265660e665df51b129e8425216ed1 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 5 Sep 2023 04:23:38 +0000 Subject: [PATCH] igmp: limit igmpv3_newpack() packet size to IP_MAX_MTU This is a follow up of commit 915d975b2ffa ("net: deal with integer overflows in kmalloc_reserve()") based on David Laight feedback. Back in 2010, I failed to realize malicious users could set dev->mtu to arbitrary values. This mtu has been since limited to 0x7fffffff but regardless of how big dev->mtu is, it makes no sense for igmpv3_newpack() to allocate more than IP_MAX_MTU and risk various skb fields overflows. Fixes: 57e1ab6eaddc ("igmp: refine skb allocations") Link: https://lore.kernel.org/netdev/d273628df80f45428e739274ab9ecb72@AcuMS.aculab.com/ Signed-off-by: Eric Dumazet Reported-by: David Laight Cc: Kyle Zeng Reviewed-by: Simon Horman Signed-off-by: David S. Miller --- net/ipv4/igmp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index 0c9e768e5628..418e5fb58fd3 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -353,8 +353,9 @@ static struct sk_buff *igmpv3_newpack(struct net_device *dev, unsigned int mtu) struct flowi4 fl4; int hlen = LL_RESERVED_SPACE(dev); int tlen = dev->needed_tailroom; - unsigned int size = mtu; + unsigned int size; + size = min(mtu, IP_MAX_MTU); while (1) { skb = alloc_skb(size + hlen + tlen, GFP_ATOMIC | __GFP_NOWARN);