diff options
| author | Florian Westphal <fw@strlen.de> | 2026-03-03 16:31:32 +0100 |
|---|---|---|
| committer | Florian Westphal <fw@strlen.de> | 2026-03-05 13:22:37 +0100 |
| commit | 9df95785d3d8302f7c066050117b04cd3c2048c2 (patch) | |
| tree | 938612ef3bd2cd56f829810493de30123c46a1ff /include | |
| parent | fb7fb4016300ac622c964069e286dc83166a5d52 (diff) | |
netfilter: nft_set_pipapo: split gc into unlink and reclaim phase
Yiming Qian reports Use-after-free in the pipapo set type:
Under a large number of expired elements, commit-time GC can run for a very
long time in a non-preemptible context, triggering soft lockup warnings and
RCU stall reports (local denial of service).
We must split GC in an unlink and a reclaim phase.
We cannot queue elements for freeing until pointers have been swapped.
Expired elements are still exposed to both the packet path and userspace
dumpers via the live copy of the data structure.
call_rcu() does not protect us: dump operations or element lookups starting
after call_rcu has fired can still observe the free'd element, unless the
commit phase has made enough progress to swap the clone and live pointers
before any new reader has picked up the old version.
This a similar approach as done recently for the rbtree backend in commit
35f83a75529a ("netfilter: nft_set_rbtree: don't gc elements on insert").
Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Reported-by: Yiming Qian <yimingqian591@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/netfilter/nf_tables.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index ea6f29ad7888..e2d2bfc1f989 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -1863,6 +1863,11 @@ struct nft_trans_gc { struct rcu_head rcu; }; +static inline int nft_trans_gc_space(const struct nft_trans_gc *trans) +{ + return NFT_TRANS_GC_BATCHCOUNT - trans->count; +} + static inline void nft_ctx_update(struct nft_ctx *ctx, const struct nft_trans *trans) { |