Date: Wed, 08 May 2024 11:04:29 -0700
From: syzbot <syzbot+68619f9e9e69accd8e0a@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [kernel?] KASAN: slab-use-after-free Read in
 kill_orphaned_pgrp (2)

Hello,

syzbot found the following issue on:

HEAD commit:    dccb07f2914c Merge tag 'for-6.9-rc7-tag' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12928970980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6d14c12b661fb43
dashboard link: https://syzkaller.appspot.com/bug?extid=68619f9e9e69accd8e0a
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bc129693f2cc/disk-dccb07f2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cf12611cfdc7/vmlinux-dccb07f2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/311fbc1afd69/bzImage-dccb07f2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+68619f9e9e69accd8e0a@...kaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in task_pgrp include/linux/sched/signal.h:689 [inline]
BUG: KASAN: slab-use-after-free in kill_orphaned_pgrp+0x41/0x560 kernel/exit.c:379
Read of size 8 at addr ffff888064362708 by task vhost-9668/9669

CPU: 0 PID: 9669 Comm: vhost-9668 Not tainted 6.9.0-rc7-syzkaller-00012-gdccb07f2914c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 task_pgrp include/linux/sched/signal.h:689 [inline]
 kill_orphaned_pgrp+0x41/0x560 kernel/exit.c:379
 exit_notify kernel/exit.c:739 [inline]
 do_exit+0x1673/0x27e0 kernel/exit.c:898
 vhost_task_fn+0x2ff/0x320 kernel/vhost_task.c:61
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Allocated by task 8534:
 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:312 [inline]
 __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:338
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slub.c:3804 [inline]
 slab_alloc_node mm/slub.c:3851 [inline]
 kmem_cache_alloc_node+0x194/0x390 mm/slub.c:3894
 alloc_task_struct_node kernel/fork.c:176 [inline]
 dup_task_struct+0x57/0x7d0 kernel/fork.c:1107
 copy_process+0x5d1/0x3df0 kernel/fork.c:2220
 kernel_clone+0x226/0x8f0 kernel/fork.c:2797
 __do_sys_clone kernel/fork.c:2940 [inline]
 __se_sys_clone kernel/fork.c:2924 [inline]
 __x64_sys_clone+0x258/0x2a0 kernel/fork.c:2924
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5326:
 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:579
 poison_slab_object+0xa6/0xe0 mm/kasan/common.c:240
 __kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2111 [inline]
 slab_free mm/slub.c:4286 [inline]
 kmem_cache_free+0x10b/0x2d0 mm/slub.c:4350
 put_task_struct include/linux/sched/task.h:138 [inline]
 delayed_put_task_struct+0x125/0x2f0 kernel/exit.c:229
 rcu_do_batch kernel/rcu/tree.c:2196 [inline]
 rcu_core+0xafd/0x1830 kernel/rcu/tree.c:2471
 handle_softirqs+0x2d6/0x990 kernel/softirq.c:554
 __do_softirq kernel/softirq.c:588 [inline]
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:649
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1043
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

Last potentially related work creation:
 kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:541
 __call_rcu_common kernel/rcu/tree.c:2734 [inline]
 call_rcu+0x167/0xa70 kernel/rcu/tree.c:2838
 release_task+0x16d2/0x1810
 de_thread fs/exec.c:1172 [inline]
 begin_new_exec+0xfde/0x1ce0 fs/exec.c:1278
 load_elf_binary+0xb12/0x2e40 fs/binfmt_elf.c:996
 search_binary_handler fs/exec.c:1778 [inline]
 exec_binprm fs/exec.c:1820 [inline]
 bprm_execve+0xaf8/0x17c0 fs/exec.c:1872
 do_execveat_common+0x553/0x700 fs/exec.c:1979
 do_execve fs/exec.c:2053 [inline]
 __do_sys_execve fs/exec.c:2129 [inline]
 __se_sys_execve fs/exec.c:2124 [inline]
 __x64_sys_execve+0x92/0xb0 fs/exec.c:2124
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888064361e00
 which belongs to the cache task_struct of size 7424
The buggy address is located 2312 bytes inside of
 freed 7424-byte region [ffff888064361e00, ffff888064363b00)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x64360
head: order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88801ed27d81
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888015eea500 ffffea00008c9e00 dead000000000002
raw: 0000000000000000 0000000000040004 00000001ffffffff ffff88801ed27d81
head: 00fff00000000840 ffff888015eea500 ffffea00008c9e00 dead000000000002
head: 0000000000000000 0000000000040004 00000001ffffffff ffff88801ed27d81
head: 00fff00000000003 ffffea000190d801 dead000000000122 00000000ffffffff
head: 0000000800000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4538, tgid -361552985 (udevd), ts 4538, free_ts 24654065279
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1534
 prep_new_page mm/page_alloc.c:1541 [inline]
 get_page_from_freelist+0x3410/0x35b0 mm/page_alloc.c:3317
 __alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575
 __alloc_pages_node include/linux/gfp.h:238 [inline]
 alloc_pages_node include/linux/gfp.h:261 [inline]
 alloc_slab_page+0x5f/0x160 mm/slub.c:2180
 allocate_slab mm/slub.c:2343 [inline]
 new_slab+0x84/0x2f0 mm/slub.c:2396
 ___slab_alloc+0xc73/0x1260 mm/slub.c:3530
 __slab_alloc mm/slub.c:3615 [inline]
 __slab_alloc_node mm/slub.c:3668 [inline]
 slab_alloc_node mm/slub.c:3841 [inline]
 kmem_cache_alloc_node+0x24a/0x390 mm/slub.c:3894
 alloc_task_struct_node kernel/fork.c:176 [inline]
 dup_task_struct+0x57/0x7d0 kernel/fork.c:1107
 copy_process+0x5d1/0x3df0 kernel/fork.c:2220
 kernel_clone+0x226/0x8f0 kernel/fork.c:2797
 __do_sys_clone kernel/fork.c:2940 [inline]
 __se_sys_clone kernel/fork.c:2924 [inline]
 __x64_sys_clone+0x258/0x2a0 kernel/fork.c:2924
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 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:1141 [inline]
 free_unref_page_prepare+0x986/0xab0 mm/page_alloc.c:2347
 free_unref_page+0x37/0x3f0 mm/page_alloc.c:2487
 free_contig_range+0x9e/0x160 mm/page_alloc.c:6572
 destroy_args+0x8a/0x890 mm/debug_vm_pgtable.c:1036
 debug_vm_pgtable+0x4be/0x550 mm/debug_vm_pgtable.c:1416
 do_one_initcall+0x248/0x880 init/main.c:1245
 do_initcall_level+0x157/0x210 init/main.c:1307
 do_initcalls+0x3f/0x80 init/main.c:1323
 kernel_init_freeable+0x435/0x5d0 init/main.c:1555
 kernel_init+0x1d/0x2b0 init/main.c:1444
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Memory state around the buggy address:
 ffff888064362600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888064362680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888064362700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff888064362780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888064362800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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