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| author | Zihan Xi <zihanx@nebusec.ai> | 2026-09-08 07:42:56 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-09-10 08:39:06 -0700 |
| commit | 19b4ed644d68098cc62ab612727f40d30f43476c (patch) | |
| tree | 40c1c6cb900b27e01b6bed9adfdc66ca2c36d60b /net | |
| parent | 5e38d732ec67a5b1f9a56e6c73add480c4b6030a (diff) | |
| download | linux-next-19b4ed644d68098cc62ab612727f40d30f43476c.tar.gz linux-next-19b4ed644d68098cc62ab612727f40d30f43476c.zip | |
ipv6: fix fib6 walker UAF on seq stop
ipv6_route_iter_active() treats a walker in FWS_U at the table root as
already unlinked. fib6_del_route() can move a still-linked walker into
that same state when the current leaf is the last route at the root,
so ipv6_route_native_seq_stop() skips fib6_walker_unlink(). The seq
private object can then be freed while it remains on
net->ipv6.fib6_walkers. A later route deletion walks the dangling list
and uses the freed walker.
Use the list head as membership state and reinitialize it when
unlinking. Keep the existing w->node check so a never-started iterator
with a zeroed private object is not treated as linked.
The same stop helper is used by /proc/net/ipv6_route and by the BPF
ipv6_route iterator. The BPF show path only widens the race.
Fixes: 8d2ca1d7b5c3 ("ipv6: avoid high order memory allocations for /proc/net/ipv6_route")
Cc: stable@vger.kernel.org
Reported-by: Vega <vega@nebusec.ai>
Co-developed-by: Luxing Yin <root@tr0jan.top>
Signed-off-by: Luxing Yin <root@tr0jan.top>
Signed-off-by: Zihan Xi <zihanx@nebusec.ai>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/89699735763f6c297584d7c2ff106239cc1e8ce0.1788837093.git.zihanx@nebusec.ai
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv6/ip6_fib.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index 3e382ba1573e..9ea75703b38d 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -85,7 +85,7 @@ static void fib6_walker_link(struct net *net, struct fib6_walker *w) static void fib6_walker_unlink(struct net *net, struct fib6_walker *w) { write_lock_bh(&net->ipv6.fib6_walker_lock); - list_del(&w->lh); + list_del_init(&w->lh); write_unlock_bh(&net->ipv6.fib6_walker_lock); } @@ -2760,7 +2760,7 @@ static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos) static bool ipv6_route_iter_active(struct ipv6_route_iter *iter) { struct fib6_walker *w = &iter->w; - return w->node && !(w->state == FWS_U && w->node == w->root); + return w->node && !list_empty(&w->lh); } static void ipv6_route_native_seq_stop(struct seq_file *seq, void *v) |