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Subject[PATCH AUTOSEL 4.18 044/100] netfilter: nft_set_rbtree: add missing rb_erase() in GC routine
Date
From: Taehee Yoo <ap420073@gmail.com>

[ Upstream commit a13f814a67b12a2f29d1decf4b4f4e700658a517 ]

The nft_set_gc_batch_check() checks whether gc buffer is full.
If gc buffer is full, gc buffer is released by
the nft_set_gc_batch_complete() internally.
In case of rbtree, the rb_erase() should be called before calling the
nft_set_gc_batch_complete(). therefore the rb_erase() should
be called before calling the nft_set_gc_batch_check() too.

test commands:
table ip filter {
set set1 {
type ipv4_addr; flags interval, timeout;
gc-interval 10s;
timeout 1s;
elements = {
1-2,
3-4,
5-6,
...
10000-10001,
}
}
}
%nft -f test.nft

splat looks like:
[ 430.273885] kasan: GPF could be caused by NULL-ptr deref or user memory access
[ 430.282158] general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
[ 430.283116] CPU: 1 PID: 190 Comm: kworker/1:2 Tainted: G B 4.18.0+ #7
[ 430.283116] Workqueue: events_power_efficient nft_rbtree_gc [nf_tables_set]
[ 430.313559] RIP: 0010:rb_next+0x81/0x130
[ 430.313559] Code: 08 49 bd 00 00 00 00 00 fc ff df 48 bb 00 00 00 00 00 fc ff df 48 85 c0 75 05 eb 58 48 89 d4
[ 430.313559] RSP: 0018:ffff88010cdb7680 EFLAGS: 00010207
[ 430.313559] RAX: 0000000000b84854 RBX: dffffc0000000000 RCX: ffffffff83f01973
[ 430.313559] RDX: 000000000017090c RSI: 0000000000000008 RDI: 0000000000b84864
[ 430.313559] RBP: ffff8801060d4588 R08: fffffbfff09bc349 R09: fffffbfff09bc349
[ 430.313559] R10: 0000000000000001 R11: fffffbfff09bc348 R12: ffff880100f081a8
[ 430.313559] R13: dffffc0000000000 R14: ffff880100ff8688 R15: dffffc0000000000
[ 430.313559] FS: 0000000000000000(0000) GS:ffff88011b400000(0000) knlGS:0000000000000000
[ 430.313559] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 430.313559] CR2: 0000000001551008 CR3: 000000005dc16000 CR4: 00000000001006e0
[ 430.313559] Call Trace:
[ 430.313559] nft_rbtree_gc+0x112/0x5c0 [nf_tables_set]
[ 430.313559] process_one_work+0xc13/0x1ec0
[ 430.313559] ? _raw_spin_unlock_irq+0x29/0x40
[ 430.313559] ? pwq_dec_nr_in_flight+0x3c0/0x3c0
[ 430.313559] ? set_load_weight+0x270/0x270
[ 430.313559] ? __switch_to_asm+0x34/0x70
[ 430.313559] ? __switch_to_asm+0x40/0x70
[ 430.313559] ? __switch_to_asm+0x34/0x70
[ 430.313559] ? __switch_to_asm+0x34/0x70
[ 430.313559] ? __switch_to_asm+0x40/0x70
[ 430.313559] ? __switch_to_asm+0x34/0x70
[ 430.313559] ? __switch_to_asm+0x40/0x70
[ 430.313559] ? __switch_to_asm+0x34/0x70
[ 430.313559] ? __switch_to_asm+0x34/0x70
[ 430.313559] ? __switch_to_asm+0x40/0x70
[ 430.313559] ? __switch_to_asm+0x34/0x70
[ 430.313559] ? __schedule+0x6d3/0x1f50
[ 430.313559] ? find_held_lock+0x39/0x1c0
[ 430.313559] ? __sched_text_start+0x8/0x8
[ 430.313559] ? cyc2ns_read_end+0x10/0x10
[ 430.313559] ? save_trace+0x300/0x300
[ 430.313559] ? sched_clock_local+0xd4/0x140
[ 430.313559] ? find_held_lock+0x39/0x1c0
[ 430.313559] ? worker_thread+0x353/0x1120
[ 430.313559] ? worker_thread+0x353/0x1120
[ 430.313559] ? lock_contended+0xe70/0xe70
[ 430.313559] ? __lock_acquire+0x4500/0x4500
[ 430.535635] ? do_raw_spin_unlock+0xa5/0x330
[ 430.535635] ? do_raw_spin_trylock+0x101/0x1a0
[ 430.535635] ? do_raw_spin_lock+0x1f0/0x1f0
[ 430.535635] ? _raw_spin_lock_irq+0x10/0x70
[ 430.535635] worker_thread+0x15d/0x1120
[ ... ]

Fixes: 8d8540c4f5e0 ("netfilter: nft_set_rbtree: add timeout support")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/netfilter/nft_set_rbtree.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/net/netfilter/nft_set_rbtree.c b/net/netfilter/nft_set_rbtree.c
index 9873d734b494..8ad78b82c8e2 100644
--- a/net/netfilter/nft_set_rbtree.c
+++ b/net/netfilter/nft_set_rbtree.c
@@ -355,12 +355,11 @@ static void nft_rbtree_walk(const struct nft_ctx *ctx,

static void nft_rbtree_gc(struct work_struct *work)
{
+ struct nft_rbtree_elem *rbe, *rbe_end = NULL, *rbe_prev = NULL;
struct nft_set_gc_batch *gcb = NULL;
- struct rb_node *node, *prev = NULL;
- struct nft_rbtree_elem *rbe;
struct nft_rbtree *priv;
+ struct rb_node *node;
struct nft_set *set;
- int i;

priv = container_of(work, struct nft_rbtree, gc_work.work);
set = nft_set_container_of(priv);
@@ -371,7 +370,7 @@ static void nft_rbtree_gc(struct work_struct *work)
rbe = rb_entry(node, struct nft_rbtree_elem, node);

if (nft_rbtree_interval_end(rbe)) {
- prev = node;
+ rbe_end = rbe;
continue;
}
if (!nft_set_elem_expired(&rbe->ext))
@@ -379,29 +378,30 @@ static void nft_rbtree_gc(struct work_struct *work)
if (nft_set_elem_mark_busy(&rbe->ext))
continue;

+ if (rbe_prev) {
+ rb_erase(&rbe_prev->node, &priv->root);
+ rbe_prev = NULL;
+ }
gcb = nft_set_gc_batch_check(set, gcb, GFP_ATOMIC);
if (!gcb)
break;

atomic_dec(&set->nelems);
nft_set_gc_batch_add(gcb, rbe);
+ rbe_prev = rbe;

- if (prev) {
- rbe = rb_entry(prev, struct nft_rbtree_elem, node);
+ if (rbe_end) {
atomic_dec(&set->nelems);
- nft_set_gc_batch_add(gcb, rbe);
- prev = NULL;
+ nft_set_gc_batch_add(gcb, rbe_end);
+ rb_erase(&rbe_end->node, &priv->root);
+ rbe_end = NULL;
}
node = rb_next(node);
if (!node)
break;
}
- if (gcb) {
- for (i = 0; i < gcb->head.cnt; i++) {
- rbe = gcb->elems[i];
- rb_erase(&rbe->node, &priv->root);
- }
- }
+ if (rbe_prev)
+ rb_erase(&rbe_prev->node, &priv->root);
write_seqcount_end(&priv->count);
write_unlock_bh(&priv->lock);

--
2.17.1
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