Messages in this thread | | | Date | Mon, 19 Feb 2024 12:18:08 +0100 | Subject | Re: [PATCH net 1/2] ioam6: fix write to cloned skb in ipv6_hop_ioam() | From | Justin Iurman <> |
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On 2/19/24 10:05, Paolo Abeni wrote: > On Sat, 2024-02-17 at 00:43 +0100, Justin Iurman wrote: >> ioam6_fill_trace_data() writes inside the skb payload without ensuring >> it's writeable (e.g., not cloned). This function is called both from the >> input and output path. The output path (ioam6_iptunnel) already does the >> check. This commit provides a fix for the input path, inside >> ipv6_hop_ioam(). >> >> Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace ") >> Reported-by: Paolo Abeni <pabeni@redhat.com> >> Signed-off-by: Justin Iurman <justin.iurman@uliege.be> >> --- >> net/ipv6/exthdrs.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c >> index 4952ae792450..f68e5faab3aa 100644 >> --- a/net/ipv6/exthdrs.c >> +++ b/net/ipv6/exthdrs.c >> @@ -943,6 +943,14 @@ static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff) >> if (!skb_valid_dst(skb)) >> ip6_route_input(skb); >> >> + if (skb_cloned(skb)) { >> + if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) >> + goto drop; > > My personal preference would be for using skb_ensure_writable() here, > with write_len == optoff + hdr->opt_len.
OK, will do!
>> + >> + hdr = (struct ioam6_hdr *)(skb_network_header(skb) + optoff); >> + trace = (struct ioam6_trace_hdr *)((u8 *)hdr + sizeof(*hdr)); > > Note that this can potentially change the network header ptr and the > caller - ip6_parse_tlv() - has cached such value in 'nh'. You also need > to update ip6_parse_tlv() to reload such pointer.
+1, I completely missed it, thanks!
> Side note: a bunch of self-tests are apparently stuck after this > series. I think it's an unrelated problem. I'll try to have a better > look.
Can you share the config to observe such behavior? I'll try to investigate too.
> Cheers, > > Paolo >
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