Message-ID: <68076b8b.050a0220.380c13.0088.GAE@google.com>
Date: Tue, 22 Apr 2025 03:12:27 -0700
From: syzbot <syzbot+c21c23281290bfafe8d5@...kaller.appspotmail.com>
To: andrii@...nel.org, ast@...nel.org, bpf@...r.kernel.org, 
	daniel@...earbox.net, davem@...emloft.net, edumazet@...gle.com, 
	horms@...nel.org, jakub@...udflare.com, john.fastabend@...il.com, 
	kuba@...nel.org, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, 
	pabeni@...hat.com, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [net?] [bpf?] KASAN: slab-use-after-free Read in
 sk_psock_verdict_data_ready (3)

Hello,

syzbot found the following issue on:

HEAD commit:    8582d9ab3efd libbpf: Verify section type in btf_find_elf_s..
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13baba3f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3b209dc5439043d2
dashboard link: https://syzkaller.appspot.com/bug?extid=c21c23281290bfafe8d5
compiler:       Debian clang version 15.0.6, Debian LLD 15.0.6

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ee77ac023e33/disk-8582d9ab.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ebe52a30453e/vmlinux-8582d9ab.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6868f9db2e2e/bzImage-8582d9ab.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c21c23281290bfafe8d5@...kaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in sk_psock_verdict_data_ready+0x6d/0x390 net/core/skmsg.c:1239
Read of size 8 at addr ffff888078595a20 by task syz.2.24/6005

CPU: 0 UID: 0 PID: 6005 Comm: syz.2.24 Not tainted 6.14.0-syzkaller-g8582d9ab3efd #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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:408 [inline]
 print_report+0x16e/0x5b0 mm/kasan/report.c:521
 kasan_report+0x143/0x180 mm/kasan/report.c:634
 sk_psock_verdict_data_ready+0x6d/0x390 net/core/skmsg.c:1239
 unix_stream_sendmsg+0x7a3/0x1000 net/unix/af_unix.c:2329
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:727
 ____sys_sendmsg+0x523/0x860 net/socket.c:2566
 ___sys_sendmsg net/socket.c:2620 [inline]
 __sys_sendmsg+0x271/0x360 net/socket.c:2652
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6d0d98e169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6d0e7fa038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f6d0dbb5fa0 RCX: 00007f6d0d98e169
RDX: 0000000000000003 RSI: 0000200000000980 RDI: 0000000000000007
RBP: 00007f6d0da10a68 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f6d0dbb5fa0 R15: 00007ffcf19f37c8
 </TASK>

Allocated by task 6005:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:319 [inline]
 __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:345
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4151 [inline]
 slab_alloc_node mm/slub.c:4200 [inline]
 kmem_cache_alloc_lru_noprof+0x1e5/0x390 mm/slub.c:4219
 sock_alloc_inode+0x28/0xc0 net/socket.c:309
 alloc_inode+0x69/0x1b0 fs/inode.c:346
 new_inode_pseudo include/linux/fs.h:3309 [inline]
 sock_alloc net/socket.c:622 [inline]
 __sock_create+0x127/0xa30 net/socket.c:1505
 sock_create net/socket.c:1599 [inline]
 __sys_socketpair+0x34f/0x720 net/socket.c:1750
 __do_sys_socketpair net/socket.c:1799 [inline]
 __se_sys_socketpair net/socket.c:1796 [inline]
 __x64_sys_socketpair+0x9b/0xb0 net/socket.c:1796
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 23:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2389 [inline]
 slab_free mm/slub.c:4646 [inline]
 kmem_cache_free+0x197/0x410 mm/slub.c:4748
 rcu_do_batch kernel/rcu/tree.c:2568 [inline]
 rcu_core+0xaac/0x17a0 kernel/rcu/tree.c:2824
 handle_softirqs+0x2d6/0x9b0 kernel/softirq.c:579
 run_ksoftirqd+0xcf/0x130 kernel/softirq.c:968
 smpboot_thread_fn+0x576/0xaa0 kernel/smpboot.c:164
 kthread+0x7b7/0x940 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Last potentially related work creation:
 kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
 kasan_record_aux_stack+0xbf/0xd0 mm/kasan/generic.c:548
 __call_rcu_common kernel/rcu/tree.c:3082 [inline]
 call_rcu+0x172/0xad0 kernel/rcu/tree.c:3202
 destroy_inode fs/inode.c:401 [inline]
 evict+0x837/0x9b0 fs/inode.c:834
 __dentry_kill+0x20d/0x630 fs/dcache.c:660
 dput+0x19f/0x2b0 fs/dcache.c:902
 __fput+0x60b/0x9f0 fs/file_table.c:473
 task_work_run+0x251/0x310 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x13f/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x210 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888078595a00
 which belongs to the cache sock_inode_cache of size 1408
The buggy address is located 32 bytes inside of
 freed 1408-byte region [ffff888078595a00, ffff888078595f80)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x78590
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888030557601
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff8881422b0dc0 0000000000000000 0000000000000001
raw: 0000000000000000 0000000000150015 00000000f5000000 ffff888030557601
head: 00fff00000000040 ffff8881422b0dc0 0000000000000000 0000000000000001
head: 0000000000000000 0000000000150015 00000000f5000000 ffff888030557601
head: 00fff00000000003 ffffea0001e16401 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Reclaimable, gfp_mask 0xd20d0(__GFP_RECLAIMABLE|__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5838, tgid 5838 (syz-executor), ts 91567346475, free_ts 30811401561
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1717
 prep_new_page mm/page_alloc.c:1725 [inline]
 get_page_from_freelist+0x352b/0x36c0 mm/page_alloc.c:3652
 __alloc_frozen_pages_noprof+0x211/0x5b0 mm/page_alloc.c:4934
 alloc_pages_mpol+0x339/0x690 mm/mempolicy.c:2301
 alloc_slab_page mm/slub.c:2459 [inline]
 allocate_slab+0x8f/0x3a0 mm/slub.c:2623
 new_slab mm/slub.c:2676 [inline]
 ___slab_alloc+0xc3b/0x1500 mm/slub.c:3862
 __slab_alloc+0x58/0xa0 mm/slub.c:3952
 __slab_alloc_node mm/slub.c:4027 [inline]
 slab_alloc_node mm/slub.c:4188 [inline]
 kmem_cache_alloc_lru_noprof+0x274/0x390 mm/slub.c:4219
 sock_alloc_inode+0x28/0xc0 net/socket.c:309
 alloc_inode+0x69/0x1b0 fs/inode.c:346
 new_inode_pseudo include/linux/fs.h:3309 [inline]
 sock_alloc net/socket.c:622 [inline]
 __sock_create+0x127/0xa30 net/socket.c:1505
 sock_create net/socket.c:1599 [inline]
 __sys_socket_create net/socket.c:1636 [inline]
 __sys_socket+0x14d/0x3c0 net/socket.c:1683
 __do_sys_socket net/socket.c:1697 [inline]
 __se_sys_socket net/socket.c:1695 [inline]
 __x64_sys_socket+0x7a/0x90 net/socket.c:1695
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 __free_frozen_pages+0xde8/0x10a0 mm/page_alloc.c:2680
 __free_pages mm/page_alloc.c:5044 [inline]
 free_contig_range+0x154/0x430 mm/page_alloc.c:6900
 destroy_args+0x94/0x4b0 mm/debug_vm_pgtable.c:1017
 debug_vm_pgtable+0x555/0x590 mm/debug_vm_pgtable.c:1397
 do_one_initcall+0x24a/0x940 init/main.c:1257
 do_initcall_level+0x157/0x210 init/main.c:1319
 do_initcalls+0x71/0xd0 init/main.c:1335
 kernel_init_freeable+0x432/0x5d0 init/main.c:1567
 kernel_init+0x1d/0x2b0 init/main.c:1457
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888078595900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888078595980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888078595a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff888078595a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888078595b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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