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| author | Jiayuan Chen <jiayuan.chen@linux.dev> | 2026-06-18 18:43:35 +0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-06-21 15:26:40 -0700 |
| commit | 9ed19e11d2146076d117d51a940643990118449b (patch) | |
| tree | f024384ffbf6fe21691c698767af94fb142a1d78 /net | |
| parent | 38becddc332c1dbee6ab8dc8f13a860c6280b905 (diff) | |
| download | ath-9ed19e11d2146076d117d51a940643990118449b.tar.gz | |
ipv6: ioam: fix type confusion of dst_entry
IOAM uses a dummy dst_entry(null_dst) to mark that the destination should
not be changed after the transformation. This dst is stored in the IOAM lwt
state and may be passed to dst_cache_set_ip6().
However, the IPv6 dst cache path eventually calls rt6_get_cookie(), which
treats the dst_entry as part of a struct rt6_info. Since the null_dst was
embedded directly as a struct dst_entry in struct ioam6_lwt, this resulted
in an invalid cast and rt6_get_cookie() reading fields from the wrong
object.
In practice, the wrong cookie is not used while dst->obsolete is zero, but
rt6_get_cookie() may also access per-cpu value when rt->sernum is
zero. In this case, rt->sernum aliases ioam6_lwt::cache::reset_ts, which
can become zero, making this a potential invalid pointer access.
Fix this by embedding a full struct rt6_info for the dummy IPv6 route and
passing its dst member to the dst APIs.
Fixes: 47ce7c854563 ("net: ipv6: ioam6: fix double reallocation")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Justin Iurman <justin.iurman@gmail.com>
Link: https://patch.msgid.link/20260618104336.48934-1-jiayuan.chen@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv6/ioam6_iptunnel.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/net/ipv6/ioam6_iptunnel.c b/net/ipv6/ioam6_iptunnel.c index b9f6d892a566c..cfb2c41634a0b 100644 --- a/net/ipv6/ioam6_iptunnel.c +++ b/net/ipv6/ioam6_iptunnel.c @@ -35,7 +35,7 @@ struct ioam6_lwt_freq { }; struct ioam6_lwt { - struct dst_entry null_dst; + struct rt6_info null_rt; struct dst_cache cache; struct ioam6_lwt_freq freq; atomic_t pkt_cnt; @@ -176,7 +176,7 @@ static int ioam6_build_state(struct net *net, struct nlattr *nla, * it is stored in the cache. Then, +1/-1 each time we read the cache * and release it. Long story short, we're fine. */ - dst_init(&ilwt->null_dst, NULL, NULL, DST_OBSOLETE_NONE, DST_NOCOUNT); + dst_init(&ilwt->null_rt.dst, NULL, NULL, DST_OBSOLETE_NONE, DST_NOCOUNT); atomic_set(&ilwt->pkt_cnt, 0); ilwt->freq.k = freq_k; @@ -360,7 +360,7 @@ static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb) /* This is how we notify that the destination does not change after * transformation and that we need to use orig_dst instead of the cache */ - if (dst == &ilwt->null_dst) { + if (dst == &ilwt->null_rt.dst) { dst_release(dst); dst = orig_dst; @@ -429,7 +429,7 @@ do_encap: local_bh_disable(); if (orig_dst->lwtstate == dst->lwtstate) dst_cache_set_ip6(&ilwt->cache, - &ilwt->null_dst, &fl6.saddr); + &ilwt->null_rt.dst, &fl6.saddr); else dst_cache_set_ip6(&ilwt->cache, dst, &fl6.saddr); local_bh_enable(); |