🇰🇷 한글 설명
Linux 커널의 page_pool 구성 요소에서 page_pool_recycle_in_ring 함수 호출 중 Use-After-Free(UAF) 취약점이 발견되었습니다. 페이지 풀이 마지막 페이지를 재활용하는 과정에서 풀 자체가 해제되어 메모리 참조 오류가 발생할 수 있습니다.
💡 쉬운 설명
컴퓨터가 사용하던 메모리 공간을 정리하는 과정에서, 이미 삭제된 메모리 영역을 다시 사용하려고 시도하여 발생하는 오류입니다. 이로 인해 시스템이 멈추거나 보안 공격에 악용될 수 있습니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
page_pool: Fix use-after-free in page_pool_recycle_in_ring
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.
📍 영향받는 시스템
Linux kernel (6.13.0-rc3 및 관련 버전 포함)
⚔️ 공격 벡터
특정 네트워크 패킷 처리 및 메모리 재활용 과정을 유도하여 커널 메모리 오류를 일으키는 방식
🛡️ 대응 방법
Linux 커널을 최신 보안 패치가 적용된 버전으로 업데이트하십시오.
🔧 검증 코드
현재 실행 중인 커널 버전을 확인하여 취약점이 해결된 패치 버전인지 확인합니다.