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.
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.
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.
Cheers,
Paolo