From: Pablo Neira Ayuso <pablo@netfilter.org> mainline inclusion from mainline-v7.0-rc1 commit def602e498a4f951da95c95b1b8ce8ae68aa733a category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/13901 CVE: CVE-2026-23272 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- In case that the set is full, a new element gets published then removed without waiting for the RCU grace period, while RCU reader can be walking over it already. To address this issue, add the element transaction even if set is full, but toggle the set_full flag to report -ENFILE so the abort path safely unwinds the set to its previous state. As for element updates, decrement set->nelems to restore it. A simpler fix is to call synchronize_rcu() in the error path. However, with a large batch adding elements to already maxed-out set, this could cause noticeable slowdown of such batches. Fixes: 35d0ac9070ef ("netfilter: nf_tables: fix set->nelems counting with no NLM_F_EXCL") Reported-by: Inseo An <y0un9sa@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Florian Westphal <fw@strlen.de> Conflicts: net/netfilter/nf_tables_api.c [commit 664899e85c13, 078996fcd657, 34aae2c2fb1e, 4201f3938914, d4b7f29eb85c and 4ee29181216d are not backport] Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/netfilter/nf_tables_api.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 649b27999102..2beef989cced 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -5581,6 +5581,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set, struct nft_data_desc desc; enum nft_registers dreg; struct nft_trans *trans; + bool set_full = false; u32 flags = 0; u64 timeout; u64 expiration; @@ -5785,10 +5786,14 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set, goto err_elem_expr; expr = NULL; + if (set->size && + atomic_inc_return(&set->nelems) > (set->size + set->ndeact)) + set_full = true; + trans = nft_trans_elem_alloc(ctx, NFT_MSG_NEWSETELEM, set); if (trans == NULL) { err = -ENOMEM; - goto err_elem_expr; + goto err_set_size; } ext->genmask = nft_genmask_cur(ctx->net); @@ -5820,20 +5825,14 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set, goto err_element_clash; } - if (set->size && - !atomic_add_unless(&set->nelems, 1, set->size + set->ndeact)) { - err = -ENFILE; - goto err_set_full; - } - nft_trans_elem(trans) = elem; nft_trans_commit_list_add_tail(ctx->net, trans); - return 0; + return set_full ? -ENFILE : 0; -err_set_full: - set->ops->remove(ctx->net, set, &elem); err_element_clash: kfree(trans); +err_set_size: + atomic_dec(&set->nelems); err_elem_expr: nf_tables_set_elem_destroy(ctx, set, elem.priv); err_parse_data: -- 2.25.1