[lvc-project] [PATCH 5.10] page_pool: Fix use-after-free in page_pool_recycle_in_ring

[Viktoriya Danchenko]

[ Upstream commit 271683bb2cf32e5126c592b5d5e6a756fa374fd9 ]

syzbot reported a uaf in page_pool_recycle_in_ring:

BUG: KASAN: slab-use-after-free in lock_release+0x151/0xa30 kernel/locking/lockdep.c:5862
Read of size 8 at addr ffff8880286045a0 by task syz.0.284/6943

CPU: 0 UID: 0 PID: 6943 Comm: syz.0.284 Not tainted 6.13.0-rc3-syzkaller-gdfa94ce54f41 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:489
 kasan_report+0x143/0x180 mm/kasan/report.c:602
 lock_release+0x151/0xa30 kernel/locking/lockdep.c:5862
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:165 [inline]
 _raw_spin_unlock_bh+0x1b/0x40 kernel/locking/spinlock.c:210
 spin_unlock_bh include/linux/spinlock.h:396 [inline]
 ptr_ring_produce_bh include/linux/ptr_ring.h:164 [inline]
 page_pool_recycle_in_ring net/core/page_pool.c:707 [inline]
 page_pool_put_unrefed_netmem+0x748/0xb00 net/core/page_pool.c:826
 page_pool_put_netmem include/net/page_pool/helpers.h:323 [inline]
 page_pool_put_full_netmem include/net/page_pool/helpers.h:353 [inline]
 napi_pp_put_page+0x149/0x2b0 net/core/skbuff.c:1036
 skb_pp_recycle net/core/skbuff.c:1047 [inline]
 skb_free_head net/core/skbuff.c:1094 [inline]
 skb_release_data+0x6c4/0x8a0 net/core/skbuff.c:1125
 skb_release_all net/core/skbuff.c:1190 [inline]
 __kfree_skb net/core/skbuff.c:1204 [inline]
 sk_skb_reason_drop+0x1c9/0x380 net/core/skbuff.c:1242
 kfree_skb_reason include/linux/skbuff.h:1263 [inline]
 __skb_queue_purge_reason include/linux/skbuff.h:3343 [inline]

root cause is:

page_pool_recycle_in_ring
  ptr_ring_produce
    spin_lock(&r->producer_lock);
    WRITE_ONCE(r->queue[r->producer++], ptr)
      //recycle last page to pool
				page_pool_release
				  page_pool_scrub
				    page_pool_empty_ring
				      ptr_ring_consume
				      page_pool_return_page  //release all page
				  __page_pool_destroy
				     free_percpu(pool->recycle_stats);
				     free(pool) //free

     spin_unlock(&r->producer_lock); //pool->ring uaf read
  recycle_stat_inc(pool, ring);

page_pool can be free while page pool recycle the last page in ring.
Add producer-lock barrier to page_pool_release to prevent the page
pool from being free before all pages have been recycled.

recycle_stat_inc() is empty when CONFIG_PAGE_POOL_STATS is not
enabled, which will trigger Wempty-body build warning. Add definition
for pool stat macro to fix warning.

Suggested-by: Jakub Kicinski <kuba at kernel.org>
Link: https://lore.kernel.org/netdev/20250513083123.3514193-1-dongchenchen2@huawei.com
Fixes: ff7d6b27f894 ("page_pool: refurbish version of page_pool code")
Reported-by: syzbot+204a4382fcb3311f3858 at syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=204a4382fcb3311f3858
Signed-off-by: Dong Chenchen <dongchenchen2 at huawei.com>
Reviewed-by: Toke Høiland-Jørgensen <toke at redhat.com>
Reviewed-by: Mina Almasry <almasrymina at google.com>
Link: https://patch.msgid
.link/20250527114152.3119109-1-dongchenchen2 at huawei.com
Signed-off-by: Jakub Kicinski <kuba at kernel.org>
[ Minor context change fixed. ]
Signed-off-by: Ruohan Lan <ruohanlan at aliyun.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Evtushenko Dmitry <d.evtushenko at omp.ru>
[ Viktoriya: add patch hunk related to newer functionality,
  namely added by:
- 368d3cb406cd ("page_pool: fix inconsistency for page_pool_ring_[un]lock()")]
Signed-off-by: Viktoriya Danchenko <v.danchenko at omp.ru>
---
Backport fix for CVE-2025-38129
---
 net/core/page_pool.c | 38 ++++++++++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 6 deletions(-)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 15ad99330bb9..b1b6f82547ac 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -21,6 +21,29 @@
 #define DEFER_TIME (msecs_to_jiffies(1000))
 #define DEFER_WARN_INTERVAL (60 * HZ)
 
+static bool page_pool_producer_lock(struct page_pool *pool)
+	__acquires(&pool->ring.producer_lock)
+{
+	bool in_softirq = in_softirq();
+
+	if (in_softirq)
+		spin_lock(&pool->ring.producer_lock);
+	else
+		spin_lock_bh(&pool->ring.producer_lock);
+
+	return in_softirq;
+}
+
+static void page_pool_producer_unlock(struct page_pool *pool,
+				      bool in_softirq)
+	__releases(&pool->ring.producer_lock)
+{
+	if (in_softirq)
+		spin_unlock(&pool->ring.producer_lock);
+	else
+		spin_unlock_bh(&pool->ring.producer_lock);
+}
+
 static int page_pool_init(struct page_pool *pool,
 			  const struct page_pool_params *params)
 {
@@ -320,14 +343,13 @@ static void page_pool_return_page(struct page_pool *pool, struct page *page)
 
 static bool page_pool_recycle_in_ring(struct page_pool *pool, struct page *page)
 {
-	int ret;
+	bool in_softirq, ret;
 	/* BH protection not needed if current is serving softirq */
-	if (in_serving_softirq())
-		ret = ptr_ring_produce(&pool->ring, page);
-	else
-		ret = ptr_ring_produce_bh(&pool->ring, page);
+	in_softirq = page_pool_producer_lock(pool);
+	ret = !__ptr_ring_produce(&pool->ring, page);
+	page_pool_producer_unlock(pool, in_softirq);
 
-	return (ret == 0) ? true : false;
+	return ret;
 }
 
 /* Only allow direct recycling in special circumstances, into the
@@ -464,10 +486,14 @@ static void page_pool_scrub(struct page_pool *pool)
 
 static int page_pool_release(struct page_pool *pool)
 {
+	bool in_softirq;
 	int inflight;
 
 	page_pool_scrub(pool);
 	inflight = page_pool_inflight(pool);
+	/* Acquire producer lock to make sure producers have exited. */
+	in_softirq = page_pool_producer_lock(pool);
+	page_pool_producer_unlock(pool, in_softirq);
 	if (!inflight)
 		page_pool_free(pool);
 
-- 
2.43.0