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:
__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.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (7.8): severity, escalated by confirmed exploitation. This CVE's 7.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it