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| author | Andrea Mayer <andrea.mayer@uniroma2.it> | 2021-12-08 22:54:09 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-12-14 12:57:09 +0300 |
| commit | 98adb2bbfa407c9290bda299d4c6f7a1c4ebd5e1 (patch) | |
| tree | 46df6ab0abf4683c98c8ac800f075681c0cb1a3d /net/ipv6 | |
| parent | f707820c09239d6f67699d9b2ff57863cc7905b0 (diff) | |
| download | linux-98adb2bbfa407c9290bda299d4c6f7a1c4ebd5e1.tar.xz | |
seg6: fix the iif in the IPv6 socket control block
commit ae68d93354e5bf5191ee673982251864ea24dd5c upstream.
When an IPv4 packet is received, the ip_rcv_core(...) sets the receiving
interface index into the IPv4 socket control block (v5.16-rc4,
net/ipv4/ip_input.c line 510):
IPCB(skb)->iif = skb->skb_iif;
If that IPv4 packet is meant to be encapsulated in an outer IPv6+SRH
header, the seg6_do_srh_encap(...) performs the required encapsulation.
In this case, the seg6_do_srh_encap function clears the IPv6 socket control
block (v5.16-rc4 net/ipv6/seg6_iptunnel.c line 163):
memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
The memset(...) was introduced in commit ef489749aae5 ("ipv6: sr: clear
IP6CB(skb) on SRH ip4ip6 encapsulation") a long time ago (2019-01-29).
Since the IPv6 socket control block and the IPv4 socket control block share
the same memory area (skb->cb), the receiving interface index info is lost
(IP6CB(skb)->iif is set to zero).
As a side effect, that condition triggers a NULL pointer dereference if
commit 0857d6f8c759 ("ipv6: When forwarding count rx stats on the orig
netdev") is applied.
To fix that issue, we set the IP6CB(skb)->iif with the index of the
receiving interface once again.
Fixes: ef489749aae5 ("ipv6: sr: clear IP6CB(skb) on SRH ip4ip6 encapsulation")
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20211208195409.12169-1-andrea.mayer@uniroma2.it
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/seg6_iptunnel.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c index 3adc5d9211ad..d64855010948 100644 --- a/net/ipv6/seg6_iptunnel.c +++ b/net/ipv6/seg6_iptunnel.c @@ -161,6 +161,14 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto) hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb)); memset(IP6CB(skb), 0, sizeof(*IP6CB(skb))); + + /* the control block has been erased, so we have to set the + * iif once again. + * We read the receiving interface index directly from the + * skb->skb_iif as it is done in the IPv4 receiving path (i.e.: + * ip_rcv_core(...)). + */ + IP6CB(skb)->iif = skb->skb_iif; } hdr->nexthdr = NEXTHDR_ROUTING; |