Message-Id: <29B3EC03-A27C-4BC6-A8C5-F7A4497D8CED@m.fudan.edu.cn>
Date: Tue, 24 Dec 2024 20:13:01 +0800
From: Kun Hu <huk23@...udan.edu.cn>
To: akpm@...ux-foundation.org,
 Liam.Howlett@...cle.com,
 lorenzo.stoakes@...cle.com,
 vbabka@...e.cz,
 jannh@...gle.com
Cc: linux-mm@...ck.org,
 linux-kernel@...r.kernel.org,
 "jjtan24@...udan.edu.cn" <jjtan24@...udan.edu.cn>
Subject: Re: [syzbot] [mm?] KASAN: slab-use-after-free Read in __mmap_region

Hello,

When using fuzzer tool to fuzz the latest Linux kernel, the following crash
was triggered.

HEAD commit: 78d4f34e2115b517bcbfe7ec0d018bbbb6f9b0b8
git tree: upstream
Console output: https://drive.google.com/file/d/1_GxT_B3JkCE8Q6r6PGgG27uNn5cgzZm3/view?usp=sharing
Kernel config: https://drive.google.com/file/d/1RhT5dFTs6Vx1U71PbpenN7TPtnPoa3NI/view?usp=sharing
C reproducer: https://drive.google.com/file/d/1zyZSM-hp1UInnE-AA9J3NXmMCV7DCqgf/view?usp=sharing
Syzlang reproducer: https://drive.google.com/file/d/1W0yvbKYi6GaAaG0YNeDVacN3eEa8rxot/view?usp=sharing

We are triggering the same issue and I hope this information is useful to you. If you fix this issue, please let me know.

==================================================================
BUG: KASAN: slab-use-after-free in __mmap_complete mm/vma.c:2408 [inline]
BUG: KASAN: slab-use-after-free in __mmap_region+0x22d6/0x2700 mm/vma.c:2469
Read of size 8 at addr ff110000085279c0 by task syz-executor339/448

CPU: 2 UID: 0 PID: 448 Comm: syz-executor339 Not tainted 6.13.0-rc3 #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1b0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcf/0x5f0 mm/kasan/report.c:489
 kasan_report+0x93/0xc0 mm/kasan/report.c:602
 __mmap_complete mm/vma.c:2408 [inline]
 __mmap_region+0x22d6/0x2700 mm/vma.c:2469
 mmap_region+0x265/0x300 mm/mmap.c:1348
 do_mmap+0xc3f/0x1000 mm/mmap.c:496
 vm_mmap_pgoff+0x1b3/0x380 mm/util.c:580
 ksys_mmap_pgoff+0x477/0x600 mm/mmap.c:542
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x127/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc3/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f53b07cbb1d
Code: c3 e8 37 2a 00 00 0f 1f 80 00 00 00 00 f3 0f 1e fa 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe3353bbe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00000000000172cc RCX: 00007f53b07cbb1d
RDX: 0000000000000008 RSI: 0000000000001000 RDI: 0000000020ffe000
RBP: 0000000000000000 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000246 R12: 00007ffe3353bc04
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Allocated by task 448:
 kasan_save_stack+0x24/0x50 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:319 [inline]
 __kasan_slab_alloc+0x87/0x90 mm/kasan/common.c:345
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4119 [inline]
 slab_alloc_node mm/slub.c:4168 [inline]
 kmem_cache_alloc_noprof+0x154/0x420 mm/slub.c:4175
 vm_area_alloc+0x20/0x200 kernel/fork.c:472
 __mmap_new_vma mm/vma.c:2340 [inline]
 __mmap_region+0x1219/0x2700 mm/vma.c:2456
 mmap_region+0x265/0x300 mm/mmap.c:1348
 do_mmap+0xc3f/0x1000 mm/mmap.c:496
 vm_mmap_pgoff+0x1b3/0x380 mm/util.c:580
 ksys_mmap_pgoff+0x477/0x600 mm/mmap.c:542
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x127/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc3/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 425:
 kasan_save_stack+0x24/0x50 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3a/0x60 mm/kasan/generic.c:582
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x54/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2353 [inline]
 slab_free mm/slub.c:4613 [inline]
 kmem_cache_free+0x126/0x4d0 mm/slub.c:4715
 rcu_do_batch kernel/rcu/tree.c:2567 [inline]
 rcu_core+0x7cb/0x16c0 kernel/rcu/tree.c:2823
 handle_softirqs+0x1ad/0x870 kernel/softirq.c:561
 __do_softirq kernel/softirq.c:595 [inline]
 invoke_softirq kernel/softirq.c:435 [inline]
 __irq_exit_rcu kernel/softirq.c:662 [inline]
 irq_exit_rcu+0xee/0x140 kernel/softirq.c:678
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0x94/0xb0 arch/x86/kernel/apic/apic.c:1049
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

Last potentially related work creation:
 kasan_save_stack+0x24/0x50 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xa6/0xc0 mm/kasan/generic.c:544
 __call_rcu_common.constprop.0+0x99/0x790 kernel/rcu/tree.c:3086
 vma_complete+0x671/0xb70 mm/vma.c:310
 commit_merge+0x7b3/0xec0 mm/vma.c:674
 vma_merge_existing_range+0xd7a/0x1f10 mm/vma.c:897
 __mmap_region+0x11e4/0x2700 mm/vma.c:2466
 mmap_region+0x265/0x300 mm/mmap.c:1348
 do_mmap+0xc3f/0x1000 mm/mmap.c:496
 vm_mmap_pgoff+0x1b3/0x380 mm/util.c:580
 ksys_mmap_pgoff+0x477/0x600 mm/mmap.c:542
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x127/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc3/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ff110000085279a0
 which belongs to the cache vm_area_struct of size 160
The buggy address is located 32 bytes inside of
 freed 160-byte region [ff110000085279a0, ff11000008527a40)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8527
anon flags: 0x100000000000000(node=0|zone=1)
page_type: f5(slab)
raw: 0100000000000000 ff110000014cb680 ffd400000019bf40 dead00000000000d
raw: 0000000000000000 0000000000120012 00000001f5000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ff11000008527880: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
 ff11000008527900: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ff11000008527980: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ff11000008527a00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ff11000008527a80: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---------------
thanks,
Kun Hu

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