syzbot


KASAN: invalid-free in init_file

Status: fixed on 2023/10/12 12:47
Subsystems: overlayfs
[Documentation on labels]
Reported-by: syzbot+ada42aab05cf51b00e98@syzkaller.appspotmail.com
Fix commit: dff745c1221a fs: move cleanup from init_file() into its callers
First crash: 338d, last: 333d
Cause bisection: introduced by (bisect log) :
commit 62d53c4a1dfe347bd87ede46ffad38c9a3870338
Author: Amir Goldstein <amir73il@gmail.com>
Date: Thu Jun 15 11:22:28 2023 +0000

  fs: use backing_file container for internal files with "fake" f_path

Crash: KASAN: invalid-free in init_file (log)
Repro: C syz .config
  
Discussions (2)
Title Replies (including bot) Last reply
[syzbot] [overlayfs?] KASAN: invalid-free in init_file 2 (5) 2023/07/02 11:03
[PATCH] fs: fix invalid-free in init_file() 1 (1) 2023/07/01 17:11
Last patch testing requests (2)
Created Duration User Patch Repo Result
2023/07/02 10:29 29m brauner@kernel.org https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.fixes OK log
2023/07/01 15:29 48m amir73il@gmail.com https://github.com/amir73il/linux.git ovl-fixes error OK

Sample crash report:
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007fbb808467a9
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005
RBP: 00007ffdc0c78ff0 R08: 0000000000000001 R09: 00007fbb80800034
R10: 000000007ffff000 R11: 0000000000000246 R12: 0000000000000006
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
==================================================================
BUG: KASAN: invalid-free in init_file+0x195/0x200 fs/file_table.c:163
Free of addr ffff88801ea5a800 by task syz-executor145/4991

CPU: 0 PID: 4991 Comm: syz-executor145 Not tainted 6.4.0-syzkaller-01224-g1ef6663a587b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:351 [inline]
 print_report+0x163/0x540 mm/kasan/report.c:462
 kasan_report_invalid_free+0xeb/0x100 mm/kasan/report.c:537
 ____kasan_slab_free+0xfb/0x120
 kasan_slab_free include/linux/kasan.h:162 [inline]
 slab_free_hook mm/slub.c:1781 [inline]
 slab_free_freelist_hook mm/slub.c:1807 [inline]
 slab_free mm/slub.c:3786 [inline]
 kmem_cache_free+0x297/0x520 mm/slub.c:3808
 init_file+0x195/0x200 fs/file_table.c:163
 alloc_empty_backing_file+0x67/0xd0 fs/file_table.c:267
 backing_file_open+0x26/0x100 fs/open.c:1166
 ovl_open_realfile+0x1f6/0x350 fs/overlayfs/file.c:64
 ovl_real_fdget_meta fs/overlayfs/file.c:122 [inline]
 ovl_real_fdget fs/overlayfs/file.c:143 [inline]
 ovl_splice_read+0x7cc/0x8c0 fs/overlayfs/file.c:430
 splice_direct_to_actor+0x2a8/0x9a0 fs/splice.c:961
 do_splice_direct+0x286/0x3d0 fs/splice.c:1070
 do_sendfile+0x623/0x1070 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fbb808467a9
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdc0c78fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007fbb808467a9
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005
RBP: 00007ffdc0c78ff0 R08: 0000000000000001 R09: 00007fbb80800034
R10: 000000007ffff000 R11: 0000000000000246 R12: 0000000000000006
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Allocated by task 4991:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:559 [inline]
 kzalloc include/linux/slab.h:680 [inline]
 alloc_empty_backing_file+0x52/0xd0 fs/file_table.c:263
 backing_file_open+0x26/0x100 fs/open.c:1166
 ovl_open_realfile+0x1f6/0x350 fs/overlayfs/file.c:64
 ovl_real_fdget_meta fs/overlayfs/file.c:122 [inline]
 ovl_real_fdget fs/overlayfs/file.c:143 [inline]
 ovl_splice_read+0x7cc/0x8c0 fs/overlayfs/file.c:430
 splice_direct_to_actor+0x2a8/0x9a0 fs/splice.c:961
 do_splice_direct+0x286/0x3d0 fs/splice.c:1070
 do_sendfile+0x623/0x1070 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88801ea5a800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 480-byte region [ffff88801ea5a800, ffff88801ea5a9e0)

The buggy address belongs to the physical page:
page:ffffea00007a9600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1ea58
head:ffffea00007a9600 order:2 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000010200 ffff888012441c80 0000000000000000 dead000000000001
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 733, tgid 733 (kworker/u4:0), ts 6534177535, free_ts 0
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1744
 prep_new_page mm/page_alloc.c:1751 [inline]
 get_page_from_freelist+0x320e/0x3390 mm/page_alloc.c:3523
 __alloc_pages+0x255/0x670 mm/page_alloc.c:4794
 alloc_slab_page+0x6a/0x160 mm/slub.c:1851
 allocate_slab mm/slub.c:1998 [inline]
 new_slab+0x84/0x2f0 mm/slub.c:2051
 ___slab_alloc+0xa85/0x10a0 mm/slub.c:3192
 __slab_alloc mm/slub.c:3291 [inline]
 __slab_alloc_node mm/slub.c:3344 [inline]
 slab_alloc_node mm/slub.c:3441 [inline]
 __kmem_cache_alloc_node+0x1b8/0x290 mm/slub.c:3490
 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1057
 kmalloc include/linux/slab.h:559 [inline]
 kzalloc include/linux/slab.h:680 [inline]
 alloc_bprm+0x56/0x900 fs/exec.c:1512
 kernel_execve+0x96/0xa10 fs/exec.c:1987
 call_usermodehelper_exec_async+0x233/0x370 kernel/umh.c:110
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88801ea5a700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801ea5a780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801ea5a800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                   ^
 ffff88801ea5a880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88801ea5a900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/06/27 14:45 upstream 1ef6663a587b 4cd5bb25 .config strace log report syz C [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: invalid-free in init_file
2023/07/02 13:44 upstream dfab92f27c60 bfc47836 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: invalid-free in init_file
2023/07/02 00:48 upstream a507db1d8fdc bfc47836 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: invalid-free in init_file
2023/07/01 10:34 upstream a507db1d8fdc af3053d2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: invalid-free in init_file
2023/06/29 20:23 upstream b19edac5992d 134ddc02 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: invalid-free in init_file
2023/06/27 14:11 upstream 1ef6663a587b 4cd5bb25 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: invalid-free in init_file
* Struck through repros no longer work on HEAD.