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KASAN: slab-use-after-free Read in ip_skb_dst_mtu

Status: fixed on 2024/05/22 23:56
Subsystems: netfilter
[Documentation on labels]
Reported-by: syzbot+e5167d7144a62715044c@syzkaller.appspotmail.com
Fix commit: 18685451fc4e inet: inet_defrag: prevent sk release while still in use
First crash: 612d, last: 571d
Cause bisection: failed (error log, bisect log)
  
▶ ▼ Discussions (8)
Title Replies (including bot) Last reply
[PATCH 4.19.y 1/1] inet: inet_defrag: prevent sk release while still in use 3 (3) 2024/12/02 18:06
[PATCH 4.19.y 1/1] inet: inet_defrag: prevent sk release while still in use 1 (1) 2024/12/02 18:04
[PATCH 5.4.y 1/1] inet: inet_defrag: prevent sk release while still in use 1 (1) 2024/09/18 22:15
[PATCH 5.10.y 1/1] inet: inet_defrag: prevent sk release while still in use 1 (1) 2024/09/18 22:15
[PATCH 5.15.y 1/1] inet: inet_defrag: prevent sk release while still in use 1 (1) 2024/09/18 22:12
[PATCH v2 net] inet: inet_defrag: prevent sk release while still in use 3 (3) 2024/03/28 11:20
[PATCH net] inet: inet_defrag: prevent sk release while still in use 3 (3) 2024/03/21 11:55
[syzbot] [netfilter?] KASAN: slab-use-after-free Read in ip_skb_dst_mtu 8 (16) 2024/03/17 10:31
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in ip_skb_dst_mtu (2) bcachefs net 19 syz done 1 242d 236d 0/29 auto-obsoleted due to no activity on 2025/06/09 18:32
linux-5.15 KASAN: use-after-free Read in ip_skb_dst_mtu origin:upstream 19 C inconclusive 2 516d 622d 0/3 auto-obsoleted due to no activity on 2024/12/14 20:26
android-5-15 KASAN: use-after-free Read in ip_skb_dst_mtu 19 1 3d07h 3d07h 0/2 premoderation: reported on 2025/10/27 00:09
▶ ▼ Last patch testing requests (8)
Created Duration User Patch Repo Result
2024/03/17 10:05 21m hdanton@sina.com patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git fe46a7dd189e report log
2024/03/16 09:00 21m hdanton@sina.com patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git fe46a7dd189e report log
2024/03/15 00:12 15m retest repro net report log
2024/03/09 08:45 24m hdanton@sina.com patch https://github.com/fbq/linux.git rcu-exp.2024.01.29b report log
2024/03/09 04:53 20m hdanton@sina.com patch https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git stable report log
2024/03/08 23:15 25m hdanton@sina.com patch https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master error
2024/03/08 12:16 20m hdanton@sina.com patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master report log
2024/03/08 10:51 14m hdanton@sina.com patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master report log

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in sk_fullsock include/net/sock.h:2823 [inline]
BUG: KASAN: slab-use-after-free in ip_skb_dst_mtu+0x830/0x9b0 include/net/ip.h:499
Read of size 1 at addr ffff88802dc5a012 by task swapper/1/0

CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.8.0-rc6-syzkaller-00037-g805d849d7c3c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x167/0x540 mm/kasan/report.c:488
 kasan_report+0x142/0x180 mm/kasan/report.c:601
 sk_fullsock include/net/sock.h:2823 [inline]
 ip_skb_dst_mtu+0x830/0x9b0 include/net/ip.h:499
 __ip_finish_output+0x12b/0x400 net/ipv4/ip_output.c:306
 ipvlan_process_v4_outbound+0x3ef/0x700 drivers/net/ipvlan/ipvlan_core.c:442
 ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:540 [inline]
 ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:602 [inline]
 ipvlan_queue_xmit+0xaa2/0x11f0 drivers/net/ipvlan/ipvlan_core.c:668
 ipvlan_start_xmit+0x4a/0x150 drivers/net/ipvlan/ipvlan_main.c:222
 __netdev_start_xmit include/linux/netdevice.h:4989 [inline]
 netdev_start_xmit include/linux/netdevice.h:5003 [inline]
 xmit_one net/core/dev.c:3547 [inline]
 dev_hard_start_xmit+0x242/0x770 net/core/dev.c:3563
 sch_direct_xmit+0x2b6/0x5f0 net/sched/sch_generic.c:342
 qdisc_restart net/sched/sch_generic.c:407 [inline]
 __qdisc_run+0xbed/0x2150 net/sched/sch_generic.c:415
 qdisc_run+0xda/0x270 include/net/pkt_sched.h:125
 net_tx_action+0x877/0xa30 net/core/dev.c:5197
 __do_softirq+0x2bb/0x942 kernel/softirq.c:553

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/02/29 17:57 upstream 805d849d7c3c 352ab904 .config strace log report syz C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce KASAN: slab-use-after-free Read in ip_skb_dst_mtu
2024/02/25 12:45 net 2a770cdc4382 8d446f15 .config strace log report syz C [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce KASAN: slab-use-after-free Read in ip_skb_dst_mtu
2024/02/25 12:45 net-next d662c5b3ce6d 8d446f15 .config strace log report syz C [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce KASAN: slab-use-after-free Read in ip_skb_dst_mtu
2024/04/07 00:21 upstream fe46a7dd189e ca620dd8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: slab-use-after-free Read in ip_skb_dst_mtu
2024/04/03 07:40 upstream fe46a7dd189e 7925100d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 KASAN: slab-use-after-free Read in ip_skb_dst_mtu
* Struck through repros no longer work on HEAD.