Re: [syzbot] [bridge?] KASAN: use-after-free Read in filemap_map_pages

[syzbot <syzbot+b72767277f29b6407083@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:495 [inline]
BUG: KASAN: slab-out-of-bounds in filemap_map_folio_range mm/filemap.c:3820 [inline]
BUG: KASAN: slab-out-of-bounds in filemap_map_pages+0x1b75/0x1f80 mm/filemap.c:3955
Read of size 8 at addr ffff88803cb81a60 by task syz-executor275/6045

CPU: 0 UID: 0 PID: 6045 Comm: syz-executor275 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x13d/0x4b0 mm/kasan/report.c:482
 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
 ptep_get include/linux/pgtable.h:495 [inline]
 filemap_map_folio_range mm/filemap.c:3820 [inline]
 filemap_map_pages+0x1b75/0x1f80 mm/filemap.c:3955
 do_fault_around mm/memory.c:5818 [inline]
 do_read_fault mm/memory.c:5851 [inline]
 do_fault+0x985/0x1750 mm/memory.c:5994
 do_pte_missing mm/memory.c:4566 [inline]
 handle_pte_fault mm/memory.c:6379 [inline]
 __handle_mm_fault+0x187d/0x2a00 mm/memory.c:6517
 handle_mm_fault+0x37b/0xa30 mm/memory.c:6686
 do_user_addr_fault+0x74c/0x12f0 arch/x86/mm/fault.c:1394
 handle_page_fault arch/x86/mm/fault.c:1483 [inline]
 exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1536
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0010:fault_in_readable+0xde/0x190 mm/gup.c:2161
Code: 68 46 ae ff 4c 89 f0 48 85 c0 0f 85 bf 00 00 00 e8 77 4c ae ff 0f 01 cb 0f ae e8 4c 89 fb 4d 85 ff 75 31 eb 48 e8 62 4c ae ff <44> 8a 33 e8 5a 4c ae ff 48 81 c3 00 10 00 00 31 ff 48 81 e3 00 f0
RSP: 0018:ffffc900030d7af8 EFLAGS: 00050293
RAX: 0000000000000000 RBX: 00007fb9fe400000 RCX: ffffffff825c2758
RDX: ffff88802a614a80 RSI: ffffffff825c271e RDI: ffff88802a614a80
RBP: 00007fb9fe400001 R08: 0000000000000006 R09: 00007fb9fe400001
R10: 00007fb9fe400000 R11: 0000000000000000 R12: 0000000000000001
R13: 1ffff9200061af60 R14: 0000000000000000 R15: 00007fb9fe400000
 fault_in_iov_iter_readable+0x101/0x2c0 lib/iov_iter.c:106
 generic_perform_write+0x863/0xa40 mm/filemap.c:4413
 shmem_file_write_iter+0x10e/0x140 mm/shmem.c:3424
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1050 fs/read_write.c:687
 ksys_pwrite64 fs/read_write.c:794 [inline]
 __do_sys_pwrite64 fs/read_write.c:802 [inline]
 __se_sys_pwrite64 fs/read_write.c:799 [inline]
 __x64_sys_pwrite64+0x1eb/0x250 fs/read_write.c:799
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb9fe9f8e5e
Code: 08 0f 85 f5 e2 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007fb9fdbfe1a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007fb9fdbfe6c0 RCX: 00007fb9fe9f8e5e
RDX: 0000000000000001 RSI: 00007fb9fe400000 RDI: 0000000000000003
RBP: 0000000000000021 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffd0
R13: 0000000000000000 R14: 00007fff5b6bda40 R15: 00007fff5b6bdb28
 </TASK>

Allocated by task 5144:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5334 [inline]
 __kvmalloc_node_noprof+0x34f/0x970 mm/slub.c:6905
 simple_xattr_alloc+0x6c/0xd0 fs/xattr.c:1271
 class_simple_xattr_constructor include/linux/xattr.h:166 [inline]
 simple_xattr_set+0xa8/0x3ca0 fs/xattr.c:1438
 shmem_xattr_handler_set+0x326/0x3c0 mm/shmem.c:4266
 __vfs_setxattr+0x175/0x1e0 fs/xattr.c:223
 __vfs_setxattr_noperm+0x127/0x660 fs/xattr.c:257
 __vfs_setxattr_locked+0x127/0x2b0 fs/xattr.c:318
 vfs_setxattr+0x14a/0x390 fs/xattr.c:344
 do_setxattr+0x145/0x180 fs/xattr.c:662
 filename_setxattr+0x167/0x1d0 fs/xattr.c:690
 path_setxattrat+0x1ff/0x3b0 fs/xattr.c:734
 __do_sys_lsetxattr fs/xattr.c:775 [inline]
 __se_sys_lsetxattr fs/xattr.c:771 [inline]
 __x64_sys_lsetxattr+0xc9/0x140 fs/xattr.c:771
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88803cb81a00
 which belongs to the cache kmalloc-cg-128 of size 128
The buggy address is located 96 bytes inside of
 allocated 98-byte region [ffff88803cb81a00, ffff88803cb81a62)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88803cb81f00 pfn:0x3cb81
flags: 0xfff00000000200(workingset|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000200 ffff88801c049b80 ffffea000161cb90 ffffea0000b6dbd0
raw: ffff88803cb81f00 000000080010000f 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 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5144, tgid 5144 (udevd), ts 32535993040, free_ts 32521083899
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304
 alloc_slab_page mm/slub.c:3266 [inline]
 allocate_slab mm/slub.c:3380 [inline]
 new_slab+0xa2/0x640 mm/slub.c:3426
 refill_objects+0xe3/0x410 mm/slub.c:7310
 refill_sheaf mm/slub.c:2804 [inline]
 __pcs_replace_empty_main+0x376/0x680 mm/slub.c:4675
 alloc_from_pcs mm/slub.c:4773 [inline]
 slab_alloc_node mm/slub.c:4905 [inline]
 __do_kmalloc_node mm/slub.c:5333 [inline]
 __kvmalloc_node_noprof+0x793/0x970 mm/slub.c:6905
 simple_xattr_alloc+0x6c/0xd0 fs/xattr.c:1271
 class_simple_xattr_constructor include/linux/xattr.h:166 [inline]
 simple_xattr_set+0xa8/0x3ca0 fs/xattr.c:1438
 shmem_xattr_handler_set+0x326/0x3c0 mm/shmem.c:4266
 __vfs_setxattr+0x175/0x1e0 fs/xattr.c:223
 __vfs_setxattr_noperm+0x127/0x660 fs/xattr.c:257
 __vfs_setxattr_locked+0x127/0x2b0 fs/xattr.c:318
 vfs_setxattr+0x14a/0x390 fs/xattr.c:344
 do_setxattr+0x145/0x180 fs/xattr.c:662
 filename_setxattr+0x167/0x1d0 fs/xattr.c:690
page last free pid 5152 tgid 5152 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4584 [inline]
 slab_alloc_node mm/slub.c:4917 [inline]
 __do_kmalloc_node mm/slub.c:5333 [inline]
 __kmalloc_noprof+0x2bf/0x820 mm/slub.c:5359
 _kmalloc_noprof include/linux/slab.h:992 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 tomoyo_encode2+0xfb/0x3c0 security/tomoyo/realpath.c:45
 tomoyo_encode+0x29/0x50 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x18c/0x690 security/tomoyo/realpath.c:283
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x276/0x460 security/tomoyo/file.c:827
 security_inode_getattr+0x116/0x280 security/security.c:1895
 vfs_getattr fs/stat.c:259 [inline]
 vfs_statx_path fs/stat.c:299 [inline]
 vfs_statx+0x11f/0x3f0 fs/stat.c:356
 vfs_fstatat+0x77/0xe0 fs/stat.c:373
 __do_sys_newfstatat+0x9d/0x120 fs/stat.c:538
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88803cb81900: 00 00 00 00 00 00 00 00 00 00 00 00 02 fc fc fc
 ffff88803cb81980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88803cb81a00: 00 00 00 00 00 00 00 00 00 00 00 00 02 fc fc fc
                                                       ^
 ffff88803cb81a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88803cb81b00: 00 00 00 00 00 00 00 00 00 00 00 00 02 fc fc fc
==================================================================
----------------
Code disassembly (best guess):
   0:	68 46 ae ff 4c       	push   $0x4cffae46
   5:	89 f0                	mov    %esi,%eax
   7:	48 85 c0             	test   %rax,%rax
   a:	0f 85 bf 00 00 00    	jne    0xcf
  10:	e8 77 4c ae ff       	call   0xffae4c8c
  15:	0f 01 cb             	stac
  18:	0f ae e8             	lfence
  1b:	4c 89 fb             	mov    %r15,%rbx
  1e:	4d 85 ff             	test   %r15,%r15
  21:	75 31                	jne    0x54
  23:	eb 48                	jmp    0x6d
  25:	e8 62 4c ae ff       	call   0xffae4c8c
* 2a:	44 8a 33             	mov    (%rbx),%r14b <-- trapping instruction
  2d:	e8 5a 4c ae ff       	call   0xffae4c8c
  32:	48 81 c3 00 10 00 00 	add    $0x1000,%rbx
  39:	31 ff                	xor    %edi,%edi
  3b:	48                   	rex.W
  3c:	81                   	.byte 0x81
  3d:	e3 00                	jrcxz  0x3f
  3f:	f0                   	lock


Tested on:

commit:         3eb40771 Merge tag 'soc-fixes-7.2-3' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1265e949580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1d67342c314f228d
dashboard link: https://syzkaller.appspot.com/bug?extid=b72767277f29b6407083
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1197b279580000