bisecting fixing commit since 7fd2bf83d59a2d32e0d596c5d3e623b9a0e7e2d5 building syzkaller on 838e7e2cd9228583ca33c49a39aea4d863d3e36d testing commit 7fd2bf83d59a2d32e0d596c5d3e623b9a0e7e2d5 compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: 1ea94d1a92e7d49dc3d6a449c0bbea04cb19022e1787c51b44fd2f33eba59b87 all runs: crashed: KASAN: use-after-free Read in consume_skb testing current HEAD 59250f8a7f3a60a2661b84cbafc1e0eb5d05ec9b testing commit 59250f8a7f3a60a2661b84cbafc1e0eb5d05ec9b compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: b5e2300abdf7b75b12a2238cdb1d93c20ce9e66dcb9bfafbedc04155d7d8ba5a all runs: crashed: KASAN: use-after-free Read in consume_skb revisions tested: 2, total time: 18m39.315792409s (build: 12m6.545790692s, test: 5m53.576234415s) the crash still happens on HEAD commit msg: Merge branch 'akpm' (patches from Andrew) crash: KASAN: use-after-free Read in consume_skb ================================================================== BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:71 [inline] BUG: KASAN: use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline] BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:147 [inline] BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:1234 [inline] BUG: KASAN: use-after-free in consume_skb+0x23/0xf0 net/core/skbuff.c:911 Read of size 4 at addr ffff88807bc175d4 by task syz-executor.4/4418 CPU: 1 PID: 4418 Comm: syz-executor.4 Not tainted 5.18.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x57/0x7d lib/dump_stack.c:106 print_address_description.constprop.0.cold+0xeb/0x495 mm/kasan/report.c:313 print_report mm/kasan/report.c:429 [inline] kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189 instrument_atomic_read include/linux/instrumented.h:71 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline] refcount_read include/linux/refcount.h:147 [inline] skb_unref include/linux/skbuff.h:1234 [inline] consume_skb+0x23/0xf0 net/core/skbuff.c:911 __sk_msg_free+0x198/0x340 net/core/skmsg.c:205 sk_msg_free net/core/skmsg.c:218 [inline] __sk_psock_purge_ingress_msg net/core/skmsg.c:757 [inline] __sk_psock_zap_ingress net/core/skmsg.c:775 [inline] sk_psock_stop+0x3f3/0x640 net/core/skmsg.c:793 sock_map_close+0x256/0x530 net/core/sock_map.c:1583 unix_release+0x6c/0xd0 net/unix/af_unix.c:989 __sock_release+0xbb/0x270 net/socket.c:650 sock_close+0xf/0x20 net/socket.c:1318 __fput+0x1f5/0x8c0 fs/file_table.c:317 task_work_run+0xc0/0x160 kernel/task_work.c:164 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop kernel/entry/common.c:169 [inline] exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:294 do_syscall_64+0x42/0x80 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7efe7de3a51b Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44 RSP: 002b:00007ffc225bac20 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000006 RCX: 00007efe7de3a51b RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000005 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000001b309200fc R10: 0000000000000000 R11: 0000000000000293 R12: 00007efe7df8cb60 R13: 00007efe7df8cb60 R14: 00007efe7df8bf60 R15: 0000000000011cfc Allocated by task 4422: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:436 [inline] __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:469 kasan_slab_alloc include/linux/kasan.h:224 [inline] slab_post_alloc_hook mm/slab.h:749 [inline] slab_alloc_node mm/slub.c:3217 [inline] slab_alloc mm/slub.c:3225 [inline] __kmem_cache_alloc_lru mm/slub.c:3232 [inline] kmem_cache_alloc+0x204/0x3b0 mm/slub.c:3242 skb_clone+0x125/0x300 net/core/skbuff.c:1520 sk_psock_verdict_recv+0x48/0x610 net/core/skmsg.c:1168 unix_read_sock+0xc4/0x1e0 net/unix/af_unix.c:2508 sk_psock_verdict_data_ready+0xf8/0x150 net/core/skmsg.c:1211 unix_dgram_sendmsg+0xca6/0x1770 net/unix/af_unix.c:2029 sock_sendmsg_nosec net/socket.c:705 [inline] sock_sendmsg+0xab/0xe0 net/socket.c:725 ____sys_sendmsg+0x38c/0x7a0 net/socket.c:2413 ___sys_sendmsg+0xd3/0x150 net/socket.c:2467 __sys_sendmmsg+0x141/0x310 net/socket.c:2553 __do_sys_sendmmsg net/socket.c:2582 [inline] __se_sys_sendmmsg net/socket.c:2579 [inline] __x64_sys_sendmmsg+0x94/0x100 net/socket.c:2579 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Freed by task 4040: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track+0x21/0x30 mm/kasan/common.c:45 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free+0x166/0x1a0 mm/kasan/common.c:328 kasan_slab_free include/linux/kasan.h:200 [inline] slab_free_hook mm/slub.c:1728 [inline] slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1754 slab_free mm/slub.c:3510 [inline] kmem_cache_free+0xdd/0x5a0 mm/slub.c:3527 kfree_skb include/linux/skbuff.h:1250 [inline] sock_drop include/linux/skmsg.h:304 [inline] sk_psock_backlog+0x871/0xd20 net/core/skmsg.c:677 process_one_work+0x865/0x13d0 kernel/workqueue.c:2289 worker_thread+0x598/0xec0 kernel/workqueue.c:2436 kthread+0x299/0x340 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 The buggy address belongs to the object at ffff88807bc17500 which belongs to the cache skbuff_head_cache of size 224 The buggy address is located 212 bytes inside of 224-byte region [ffff88807bc17500, ffff88807bc175e0) The buggy address belongs to the physical page: page:ffffea0001ef05c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7bc17 memcg:ffff88805fdbea01 flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 0000000000000000 dead000000000122 ffff888014c04500 raw: 0000000000000000 00000000000c000c 00000001ffffffff ffff88805fdbea01 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 4414, tgid 4407 (syz-executor.2), ts 72989884709, free_ts 72952731747 prep_new_page mm/page_alloc.c:2441 [inline] get_page_from_freelist+0x178d/0x3dc0 mm/page_alloc.c:4182 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5408 alloc_slab_page mm/slub.c:1799 [inline] allocate_slab+0x26c/0x3c0 mm/slub.c:1944 new_slab mm/slub.c:2004 [inline] ___slab_alloc+0x8e1/0xf20 mm/slub.c:3005 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3092 slab_alloc_node mm/slub.c:3183 [inline] kmem_cache_alloc_node+0x122/0x3f0 mm/slub.c:3267 __alloc_skb+0x151/0x270 net/core/skbuff.c:414 alloc_skb include/linux/skbuff.h:1300 [inline] alloc_skb_with_frags+0x72/0x700 net/core/skbuff.c:5995 sock_alloc_send_pskb+0x636/0x7c0 net/core/sock.c:2600 unix_dgram_sendmsg+0x35a/0x1770 net/unix/af_unix.c:1896 sock_sendmsg_nosec net/socket.c:705 [inline] sock_sendmsg+0xab/0xe0 net/socket.c:725 ____sys_sendmsg+0x38c/0x7a0 net/socket.c:2413 ___sys_sendmsg+0xd3/0x150 net/socket.c:2467 __sys_sendmmsg+0x141/0x310 net/socket.c:2553 __do_sys_sendmmsg net/socket.c:2582 [inline] __se_sys_sendmmsg net/socket.c:2579 [inline] __x64_sys_sendmmsg+0x94/0x100 net/socket.c:2579 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1356 [inline] free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1406 free_unref_page_prepare mm/page_alloc.c:3328 [inline] free_unref_page+0x19/0x6a0 mm/page_alloc.c:3423 qlink_free mm/kasan/quarantine.c:157 [inline] qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:176 kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:283 __kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:446 kasan_slab_alloc include/linux/kasan.h:224 [inline] slab_post_alloc_hook mm/slab.h:749 [inline] slab_alloc_node mm/slub.c:3217 [inline] slab_alloc mm/slub.c:3225 [inline] __kmem_cache_alloc_lru mm/slub.c:3232 [inline] kmem_cache_alloc+0x204/0x3b0 mm/slub.c:3242 prepare_creds+0x39/0x610 kernel/cred.c:260 access_override_creds fs/open.c:352 [inline] do_faccessat+0x273/0x660 fs/open.c:416 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Memory state around the buggy address: ffff88807bc17480: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc ffff88807bc17500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88807bc17580: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff88807bc17600: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ffff88807bc17680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================