Message-ID: <67afec76.050a0220.21dd3.0060.GAE@google.com>
Date: Fri, 14 Feb 2025 17:23:02 -0800
From: syzbot <syzbot+e1dc29a4daf3f8051130@...kaller.appspotmail.com>
To: eadavis@...com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [netfs?] KASAN: slab-use-after-free Write in io_submit_one

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Write in netfs_read_collection

==================================================================
BUG: KASAN: slab-use-after-free in netfs_rreq_assess_dio fs/netfs/read_collect.c:377 [inline]
BUG: KASAN: slab-use-after-free in netfs_read_collection+0x3baa/0x3d10 fs/netfs/read_collect.c:440
Write of size 8 at addr ffff8880310c6650 by task kworker/u32:2/45

CPU: 0 UID: 0 PID: 45 Comm: kworker/u32:2 Not tainted 6.14.0-rc2-syzkaller-g78a632a2086c-dirty #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: events_unbound netfs_read_collection_worker
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xc3/0x620 mm/kasan/report.c:489
 kasan_report+0xd9/0x110 mm/kasan/report.c:602
 netfs_rreq_assess_dio fs/netfs/read_collect.c:377 [inline]
 netfs_read_collection+0x3baa/0x3d10 fs/netfs/read_collect.c:440
 netfs_read_collection_worker+0x285/0x350 fs/netfs/read_collect.c:466
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3317 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3398
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Allocated by task 6706:
 kasan_save_stack+0x33/0x60 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+0x89/0x90 mm/kasan/common.c:345
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4115 [inline]
 slab_alloc_node mm/slub.c:4164 [inline]
 kmem_cache_alloc_noprof+0x226/0x3d0 mm/slub.c:4171
 aio_get_req fs/aio.c:1058 [inline]
 io_submit_one+0x123/0x1da0 fs/aio.c:2048
 __do_sys_io_submit fs/aio.c:2111 [inline]
 __se_sys_io_submit fs/aio.c:2081 [inline]
 __x64_sys_io_submit+0x1b2/0x340 fs/aio.c:2081
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 45:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x51/0x70 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:4609 [inline]
 kmem_cache_free+0x2e2/0x4d0 mm/slub.c:4711
 iocb_destroy fs/aio.c:1110 [inline]
 iocb_put fs/aio.c:1210 [inline]
 iocb_put fs/aio.c:1206 [inline]
 aio_complete_rw+0x3ec/0x7b0 fs/aio.c:1507
 netfs_rreq_assess_dio fs/netfs/read_collect.c:375 [inline]
 netfs_read_collection+0x30b3/0x3d10 fs/netfs/read_collect.c:440
 netfs_read_collection_worker+0x285/0x350 fs/netfs/read_collect.c:466
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3317 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3398
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The buggy address belongs to the object at ffff8880310c6640
 which belongs to the cache aio_kiocb of size 216
The buggy address is located 16 bytes inside of
 freed 216-byte region [ffff8880310c6640, ffff8880310c6718)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880310c7e00 pfn:0x310c6
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801bb3bcc0 0000000000000000 0000000000000001
raw: ffff8880310c7e00 0000000080190015 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801bb3bcc0 0000000000000000 0000000000000001
head: ffff8880310c7e00 0000000080190015 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea0000c43181 ffffffffffffffff 0000000000000000
head: ffff888000000002 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6549, tgid 6548 (syz.0.17), ts 88470255044, free_ts 87864364394
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x181/0x1b0 mm/page_alloc.c:1551
 prep_new_page mm/page_alloc.c:1559 [inline]
 get_page_from_freelist+0xfce/0x2f80 mm/page_alloc.c:3477
 __alloc_frozen_pages_noprof+0x221/0x2470 mm/page_alloc.c:4739
 alloc_pages_mpol+0x1fc/0x540 mm/mempolicy.c:2270
 alloc_slab_page mm/slub.c:2423 [inline]
 allocate_slab mm/slub.c:2587 [inline]
 new_slab+0x23d/0x330 mm/slub.c:2640
 ___slab_alloc+0xc5d/0x1720 mm/slub.c:3826
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3916
 __slab_alloc_node mm/slub.c:3991 [inline]
 slab_alloc_node mm/slub.c:4152 [inline]
 kmem_cache_alloc_noprof+0xfa/0x3d0 mm/slub.c:4171
 aio_get_req fs/aio.c:1058 [inline]
 io_submit_one+0x123/0x1da0 fs/aio.c:2048
 __do_sys_io_submit fs/aio.c:2111 [inline]
 __se_sys_io_submit fs/aio.c:2081 [inline]
 __x64_sys_io_submit+0x1b2/0x340 fs/aio.c:2081
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 6535 tgid 6535 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_frozen_pages+0x6db/0xfb0 mm/page_alloc.c:2660
 mm_free_pgd kernel/fork.c:815 [inline]
 __mmdrop+0xd5/0x460 kernel/fork.c:931
 mmdrop include/linux/sched/mm.h:55 [inline]
 __mmput+0x36c/0x410 kernel/fork.c:1367
 mmput+0x62/0x70 kernel/fork.c:1378
 exec_mmap fs/exec.c:1011 [inline]
 begin_new_exec+0x152b/0x3800 fs/exec.c:1267
 load_elf_binary+0x886/0x4fc0 fs/binfmt_elf.c:1002
 search_binary_handler fs/exec.c:1775 [inline]
 exec_binprm fs/exec.c:1807 [inline]
 bprm_execve fs/exec.c:1859 [inline]
 bprm_execve+0x8dd/0x16d0 fs/exec.c:1835
 do_execveat_common.isra.0+0x4a2/0x610 fs/exec.c:1966
 do_execve fs/exec.c:2040 [inline]
 __do_sys_execve fs/exec.c:2116 [inline]
 __se_sys_execve fs/exec.c:2111 [inline]
 __x64_sys_execve+0x8c/0xb0 fs/exec.c:2111
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8880310c6500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880310c6580: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc
>ffff8880310c6600: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
                                                 ^
 ffff8880310c6680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880310c6700: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


Tested on:

commit:         78a632a2 Merge tag 'pci-v6.14-fixes-3' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=159267df980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c09dc55ba7f798e3
dashboard link: https://syzkaller.appspot.com/bug?extid=e1dc29a4daf3f8051130
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=10178bf8580000

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