KASAN: use-after-free Read in unix_stream_read_actor

Status: fixed on 2023/12/13 18:20
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+5064f17718d4ca803813@syzkaller.appspotmail.com
Fix commit: 4b7b492615cf af_unix: fix use-after-free in unix_stream_read_actor()
First crash: 993d, last: 992d
Fix bisection: fixed by (bisect log) :
commit 75bcfc188abf4fae9c1d5f5dc0a03540be602eef
Author: Eric Dumazet <edumazet@google.com>
Date: Mon Nov 13 13:49:38 2023 +0000

  af_unix: fix use-after-free in unix_stream_read_actor()

  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2023/11/11 linux-5.15.y (ToT) 80529b4968a8 C [report] KASAN: use-after-free Read in unix_stream_read_actor
2023/11/11 upstream (ToT) 3ca112b71f35 C Didn't crash
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 KASAN: use-after-free Read in unix_stream_read_actor missing-backport origin:upstream 19 syz, C done done 2 919d 993d 0/2 auto-obsoleted due to no activity on 2024/05/03 09:45
linux-6.1 KASAN: use-after-free Read in unix_stream_read_actor origin:lts-only 19 syz, C done 1 989d 993d 3/3 fixed on 2023/12/18 16:47
android-5-15 KASAN: use-after-free Read in unix_stream_read_actor origin:upstream 19 syz, C 1 993d 993d 0/2 auto-obsoleted due to no activity on 2024/02/19 03:43
upstream KASAN: slab-use-after-free Read in unix_stream_read_actor (2) net 19 syz, C inconclusive 4 699d 695d 28/29 fixed on 2024/10/22 11:56
upstream KASAN: slab-use-after-free Read in unix_stream_read_actor net 19 syz, C error 6 977d 993d 25/29 fixed on 2024/01/20 21:18
android-6-12 KASAN: slab-use-after-free Read in unix_stream_read_actor origin:lts 19 syz, C 2 383d 383d 0/1 auto-obsoleted due to no activity on 2025/10/11 14:25
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2023/12/12 23:24 3h30m bisect fix linux-5.15.y OK (1) job log
2023/11/12 15:31 1h30m fix candidate upstream OK (0) job log log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in unix_stream_read_actor+0x9e/0xa0 net/unix/af_unix.c:2809
Read of size 4 at addr ffff88801a231684 by task syz-executor758/3526

CPU: 1 PID: 3526 Comm: syz-executor758 Not tainted 5.15.138-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_address_description+0x63/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0x16b/0x1c0 mm/kasan/report.c:451
 unix_stream_read_actor+0x9e/0xa0 net/unix/af_unix.c:2809
 unix_stream_recv_urg+0x1bb/0x300 net/unix/af_unix.c:2535
 unix_stream_read_generic+0x21ab/0x22a0 net/unix/af_unix.c:2615
 unix_stream_recvmsg+0x22d/0x2c0 net/unix/af_unix.c:2847
 ____sys_recvmsg+0x286/0x530
 ___sys_recvmsg+0x1ec/0x690 net/socket.c:2690
 __sys_recvmsg net/socket.c:2720 [inline]
 __do_sys_recvmsg net/socket.c:2730 [inline]
 __se_sys_recvmsg net/socket.c:2727 [inline]
 __x64_sys_recvmsg+0x1dc/0x2b0 net/socket.c:2727
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f522e1634e9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f522e0e2228 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 00007f522e1634e9
RDX: 0000000040010083 RSI: 0000000020000140 RDI: 0000000000000004
RBP: 00007f522e1ed348 R08: 00007f522e0e26c0 R09: 00007f522e0e26c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f522e1ed340
R13: 00007f522e1ed34c R14: 00007fff5b9c08c0 R15: 00007fff5b9c09a8
 </TASK>

Allocated by task 3525:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x8e/0xc0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x53/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3220 [inline]
 kmem_cache_alloc_node+0x121/0x2c0 mm/slub.c:3256
 __alloc_skb+0xdd/0x590 net/core/skbuff.c:415
 alloc_skb include/linux/skbuff.h:1167 [inline]
 alloc_skb_with_frags+0xa3/0x780 net/core/skbuff.c:6132
 sock_alloc_send_pskb+0x915/0xa50 net/core/sock.c:2512
 queue_oob+0xfd/0x8d0 net/unix/af_unix.c:1980
 unix_stream_sendmsg+0xe0a/0x1070 net/unix/af_unix.c:2117
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2429
 ___sys_sendmsg+0x252/0x2e0 net/socket.c:2483
 __sys_sendmsg net/socket.c:2512 [inline]
 __do_sys_sendmsg net/socket.c:2521 [inline]
 __se_sys_sendmsg+0x19a/0x260 net/socket.c:2519
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 3525:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x80 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd8/0x120 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1705 [inline]
 slab_free_freelist_hook+0xdd/0x160 mm/slub.c:1731
 slab_free mm/slub.c:3499 [inline]
 kmem_cache_free+0x91/0x1f0 mm/slub.c:3515
 queue_oob+0x524/0x8d0 net/unix/af_unix.c:2011
 unix_stream_sendmsg+0xe0a/0x1070 net/unix/af_unix.c:2117
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2429
 ___sys_sendmsg+0x252/0x2e0 net/socket.c:2483
 __sys_sendmsg net/socket.c:2512 [inline]
 __do_sys_sendmsg net/socket.c:2521 [inline]
 __se_sys_sendmsg+0x19a/0x260 net/socket.c:2519
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff88801a231640
 which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 68 bytes inside of
 232-byte region [ffff88801a231640, ffff88801a231728)
The buggy address belongs to the page:
page:ffffea0000688c40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1a231
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 0000000000000000 dead000000000122 ffff8880165e8500
raw: 0000000000000000 00000000000c000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 3525, ts 52575496142, free_ts 45832208612
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x322a/0x33c0 mm/page_alloc.c:4159
 __alloc_pages+0x272/0x700 mm/page_alloc.c:5421
 alloc_slab_page mm/slub.c:1775 [inline]
 allocate_slab mm/slub.c:1912 [inline]
 new_slab+0xbb/0x4b0 mm/slub.c:1975
 ___slab_alloc+0x6f6/0xe10 mm/slub.c:3008
 __slab_alloc mm/slub.c:3095 [inline]
 slab_alloc_node mm/slub.c:3186 [inline]
 kmem_cache_alloc_node+0x1ba/0x2c0 mm/slub.c:3256
 __alloc_skb+0xdd/0x590 net/core/skbuff.c:415
 alloc_skb include/linux/skbuff.h:1167 [inline]
 alloc_skb_with_frags+0xa3/0x780 net/core/skbuff.c:6132
 sock_alloc_send_pskb+0x915/0xa50 net/core/sock.c:2512
 queue_oob+0xfd/0x8d0 net/unix/af_unix.c:1980
 unix_stream_sendmsg+0xe0a/0x1070 net/unix/af_unix.c:2117
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2429
 ___sys_sendmsg+0x252/0x2e0 net/socket.c:2483
 __sys_sendmsg net/socket.c:2512 [inline]
 __do_sys_sendmsg net/socket.c:2521 [inline]
 __se_sys_sendmsg+0x19a/0x260 net/socket.c:2519
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0xc34/0xcf0 mm/page_alloc.c:3317
 free_unref_page+0x95/0x2d0 mm/page_alloc.c:3396
 pipe_buf_release include/linux/pipe_fs_i.h:203 [inline]
 pipe_read+0x6e4/0x12b0 fs/pipe.c:323
 call_read_iter include/linux/fs.h:2097 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0xa9f/0xe10 fs/read_write.c:485
 ksys_read+0x1a2/0x2c0 fs/read_write.c:623
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff88801a231580: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
 ffff88801a231600: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
>ffff88801a231680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88801a231700: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
 ffff88801a231780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/11/11 04:31 linux-5.15.y 80529b4968a8 d80eec66 .config console log report syz C ci2-linux-5-15-kasan-perf KASAN: use-after-free Read in unix_stream_read_actor
* Struck through repros no longer work on HEAD.