Re: [syzbot] [mm?] WARNING in __folio_rmap_sanity_checks (2)

[syzbot <syzbot+c0673e1f1f054fac28c2@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-out-of-bounds Read in filemap_map_pages

==================================================================
BUG: KASAN: slab-out-of-bounds in ptep_get include/linux/pgtable.h:338 [inline]
BUG: KASAN: slab-out-of-bounds in filemap_map_folio_range mm/filemap.c:3632 [inline]
BUG: KASAN: slab-out-of-bounds in filemap_map_pages+0xde4/0x1aa0 mm/filemap.c:3749
Read of size 8 at addr ffff8880622b9010 by task syz.3.68/7906

CPU: 1 UID: 0 PID: 7906 Comm: syz.3.68 Not tainted 6.13.0-rc3-next-20241220-syzkaller-05236-g8155b4ef3466-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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:378 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:489
 kasan_report+0x143/0x180 mm/kasan/report.c:602
 ptep_get include/linux/pgtable.h:338 [inline]
 filemap_map_folio_range mm/filemap.c:3632 [inline]
 filemap_map_pages+0xde4/0x1aa0 mm/filemap.c:3749
 do_fault_around mm/memory.c:5351 [inline]
 do_read_fault mm/memory.c:5384 [inline]
 do_fault mm/memory.c:5527 [inline]
 do_pte_missing mm/memory.c:4048 [inline]
 handle_pte_fault+0x3888/0x5ee0 mm/memory.c:5890
 __handle_mm_fault mm/memory.c:6033 [inline]
 handle_mm_fault+0x11f5/0x1d50 mm/memory.c:6202
 faultin_page mm/gup.c:1196 [inline]
 __get_user_pages+0x1a92/0x4140 mm/gup.c:1491
 populate_vma_page_range+0x264/0x330 mm/gup.c:1929
 __mm_populate+0x27a/0x460 mm/gup.c:2032
 mm_populate include/linux/mm.h:3400 [inline]
 vm_mmap_pgoff+0x303/0x430 mm/util.c:585
 ksys_mmap_pgoff+0x4eb/0x720 mm/mmap.c:607
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4084f85d29
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:00007f4085da6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f4085176080 RCX: 00007f4084f85d29
RDX: 0000000000000002 RSI: 0000000000b36000 RDI: 0000000020000000
RBP: 00007f4085001b08 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000028011 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f4085176080 R15: 00007fff8010b888
 </TASK>

Allocated by task 5846:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4294 [inline]
 __kmalloc_node_noprof+0x290/0x4d0 mm/slub.c:4300
 kmalloc_array_node_noprof include/linux/slab.h:1018 [inline]
 alloc_slab_obj_exts mm/slub.c:1964 [inline]
 account_slab mm/slub.c:2550 [inline]
 allocate_slab+0x179/0x3a0 mm/slub.c:2605
 new_slab mm/slub.c:2640 [inline]
 ___slab_alloc+0xc27/0x14a0 mm/slub.c:3826
 __slab_alloc+0x58/0xa0 mm/slub.c:3916
 __slab_alloc_node mm/slub.c:3991 [inline]
 slab_alloc_node mm/slub.c:4152 [inline]
 __do_kmalloc_node mm/slub.c:4293 [inline]
 __kmalloc_node_noprof+0x2ee/0x4d0 mm/slub.c:4300
 __kvmalloc_node_noprof+0x72/0x190 mm/util.c:667
 alloc_netdev_mqs+0xa4/0x1080 net/core/dev.c:11209
 rtnl_create_link+0x2f9/0xc20 net/core/rtnetlink.c:3595
 rtnl_newlink_create+0x210/0xa40 net/core/rtnetlink.c:3771
 __rtnl_newlink net/core/rtnetlink.c:3897 [inline]
 rtnl_newlink+0x1c7e/0x2210 net/core/rtnetlink.c:4012
 rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6902
 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2542
 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]
 netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1347
 netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1891
 sock_sendmsg_nosec net/socket.c:711 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:726
 __sys_sendto+0x363/0x4c0 net/socket.c:2208
 __do_sys_sendto net/socket.c:2215 [inline]
 __se_sys_sendto net/socket.c:2211 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2211
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880622b9000
 which belongs to the cache kmalloc-16 of size 16
The buggy address is located 0 bytes to the right of
 allocated 16-byte region [ffff8880622b9000, ffff8880622b9010)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x622b9
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801ac41640 ffffea0000cbd080 dead000000000002
raw: 0000000000000000 0000000000800080 00000000f5000000 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 0x252800(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP|__GFP_THISNODE), pid 5846, tgid 5846 (syz-executor), ts 70570504990, free_ts 70568138444
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1551
 prep_new_page mm/page_alloc.c:1559 [inline]
 get_page_from_freelist+0x365c/0x37a0 mm/page_alloc.c:3477
 __alloc_frozen_pages_noprof+0x292/0x710 mm/page_alloc.c:4754
 alloc_slab_page mm/slub.c:2425 [inline]
 allocate_slab+0x66/0x3a0 mm/slub.c:2587
 new_slab mm/slub.c:2640 [inline]
 ___slab_alloc+0xc27/0x14a0 mm/slub.c:3826
 __slab_alloc+0x58/0xa0 mm/slub.c:3916
 __slab_alloc_node mm/slub.c:3991 [inline]
 slab_alloc_node mm/slub.c:4152 [inline]
 __do_kmalloc_node mm/slub.c:4293 [inline]
 __kmalloc_node_noprof+0x2ee/0x4d0 mm/slub.c:4300
 kmalloc_array_node_noprof include/linux/slab.h:1018 [inline]
 alloc_slab_obj_exts mm/slub.c:1964 [inline]
 account_slab mm/slub.c:2550 [inline]
 allocate_slab+0x179/0x3a0 mm/slub.c:2605
 new_slab mm/slub.c:2640 [inline]
 ___slab_alloc+0xc27/0x14a0 mm/slub.c:3826
 __slab_alloc+0x58/0xa0 mm/slub.c:3916
 __slab_alloc_node mm/slub.c:3991 [inline]
 slab_alloc_node mm/slub.c:4152 [inline]
 __do_kmalloc_node mm/slub.c:4293 [inline]
 __kmalloc_node_noprof+0x2ee/0x4d0 mm/slub.c:4300
 __kvmalloc_node_noprof+0x72/0x190 mm/util.c:667
 alloc_netdev_mqs+0xa4/0x1080 net/core/dev.c:11209
 rtnl_create_link+0x2f9/0xc20 net/core/rtnetlink.c:3595
 rtnl_newlink_create+0x210/0xa40 net/core/rtnetlink.c:3771
 __rtnl_newlink net/core/rtnetlink.c:3897 [inline]
 rtnl_newlink+0x1c7e/0x2210 net/core/rtnetlink.c:4012
page last free pid 5890 tgid 5890 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_frozen_pages+0xe0d/0x10e0 mm/page_alloc.c:2660
 vfree+0x1c3/0x360 mm/vmalloc.c:3383
 kcov_put kernel/kcov.c:439 [inline]
 kcov_close+0x28/0x50 kernel/kcov.c:535
 __fput+0x3e9/0x9f0 fs/file_table.c:450
 task_work_run+0x24f/0x310 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xa2f/0x28e0 kernel/exit.c:938
 do_group_exit+0x207/0x2c0 kernel/exit.c:1087
 get_signal+0x16b2/0x1750 kernel/signal.c:3017
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [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+0xce/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8880622b8f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880622b8f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880622b9000: 00 00 fc fc fa fb fc fc fa fb fc fc 00 00 fc fc
                         ^
 ffff8880622b9080: 00 00 fc fc 00 00 fc fc 00 00 fc fc 00 00 fc fc
 ffff8880622b9100: fa fb fc fc fa fb fc fc 00 00 fc fc 00 00 fc fc
==================================================================


Tested on:

commit:         8155b4ef Add linux-next specific files for 20241220
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13b3d0b0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9c90bb7161a56c88
dashboard link: https://syzkaller.appspot.com/bug?extid=c0673e1f1f054fac28c2
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1156c818580000