KASAN: use-after-free Read in iput (2)

KASAN: use-after-free Read in iput (2)
Status: upstream: reported on 2020/11/22 21:23
Reported-by: syzbot+2cc8170bf3401fadbbfd@syzkaller.appspotmail.com
First crash: 67d, last: 8d08h

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
android-49	KASAN: use-after-free Read in iput				1	719d	651d	0/3	auto-closed as invalid on 2019/08/05 02:50
upstream	KASAN: use-after-free Read in iput	C			2	1013d	1013d	9/17	fixed on 2018/07/08 03:16

Sample crash report:

==================================================================
BUG: KASAN: use-after-free in iput+0x6b/0x70 fs/inode.c:1669
Read of size 8 at addr ffff8880929db458 by task syz-executor.0/21285

CPU: 0 PID: 21285 Comm: syz-executor.0 Not tainted 5.11.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:230
 __kasan_report mm/kasan/report.c:396 [inline]
 kasan_report.cold+0x79/0xd5 mm/kasan/report.c:413
 iput+0x6b/0x70 fs/inode.c:1669
 init_statfs fs/gfs2/ops_fstype.c:684 [inline]
 init_journal fs/gfs2/ops_fstype.c:788 [inline]
 init_inodes+0x2103/0x2650 fs/gfs2/ops_fstype.c:857
 gfs2_fill_super+0x1ae8/0x2580 fs/gfs2/ops_fstype.c:1184
 get_tree_bdev+0x440/0x760 fs/super.c:1291
 gfs2_get_tree+0x4a/0x270 fs/gfs2/ops_fstype.c:1260
 vfs_get_tree+0x89/0x2f0 fs/super.c:1496
 do_new_mount fs/namespace.c:2878 [inline]
 path_mount+0x13ad/0x20c0 fs/namespace.c:3208
 do_mount fs/namespace.c:3221 [inline]
 __do_sys_mount fs/namespace.c:3429 [inline]
 __se_sys_mount fs/namespace.c:3406 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3406
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x460c6a
Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 ad 89 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 8a 89 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007f7522e87a78 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f7522e87b10 RCX: 0000000000460c6a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f7522e87ad0
RBP: 00007f7522e87ad0 R08: 00007f7522e87b10 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000200 R15: 0000000020047a20

Allocated by task 21285:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:401 [inline]
 ____kasan_kmalloc.constprop.0+0x82/0xa0 mm/kasan/common.c:429
 kasan_slab_alloc include/linux/kasan.h:209 [inline]
 slab_post_alloc_hook mm/slab.h:512 [inline]
 slab_alloc_node mm/slub.c:2891 [inline]
 slab_alloc mm/slub.c:2899 [inline]
 kmem_cache_alloc+0x1c6/0x440 mm/slub.c:2904
 gfs2_alloc_inode+0x38/0x1a0 fs/gfs2/super.c:1546
 alloc_inode+0x61/0x230 fs/inode.c:233
 iget5_locked fs/inode.c:1147 [inline]
 iget5_locked+0x1dd/0x2d0 fs/inode.c:1140
 gfs2_iget fs/gfs2/inode.c:64 [inline]
 gfs2_inode_lookup+0x104/0xb10 fs/gfs2/inode.c:140
 gfs2_dir_search+0x20f/0x2c0 fs/gfs2/dir.c:1662
 gfs2_lookupi+0x46e/0x630 fs/gfs2/inode.c:333
 gfs2_lookup_simple+0x99/0xe0 fs/gfs2/inode.c:273
 init_statfs fs/gfs2/ops_fstype.c:641 [inline]
 init_journal fs/gfs2/ops_fstype.c:788 [inline]
 init_inodes+0x169d/0x2650 fs/gfs2/ops_fstype.c:857
 gfs2_fill_super+0x1ae8/0x2580 fs/gfs2/ops_fstype.c:1184
 get_tree_bdev+0x440/0x760 fs/super.c:1291
 gfs2_get_tree+0x4a/0x270 fs/gfs2/ops_fstype.c:1260
 vfs_get_tree+0x89/0x2f0 fs/super.c:1496
 do_new_mount fs/namespace.c:2878 [inline]
 path_mount+0x13ad/0x20c0 fs/namespace.c:3208
 do_mount fs/namespace.c:3221 [inline]
 __do_sys_mount fs/namespace.c:3429 [inline]
 __se_sys_mount fs/namespace.c:3406 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3406
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 21280:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:356
 ____kasan_slab_free+0xe1/0x110 mm/kasan/common.c:362
 kasan_slab_free include/linux/kasan.h:192 [inline]
 slab_free_hook mm/slub.c:1547 [inline]
 slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1580
 slab_free mm/slub.c:3142 [inline]
 kmem_cache_free+0x82/0x350 mm/slub.c:3158
 i_callback+0x3f/0x70 fs/inode.c:222
 rcu_do_batch kernel/rcu/tree.c:2489 [inline]
 rcu_core+0x5eb/0xf00 kernel/rcu/tree.c:2723
 __do_softirq+0x2bc/0xa29 kernel/softirq.c:343

Last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xc5/0xf0 mm/kasan/generic.c:344
 __call_rcu kernel/rcu/tree.c:2965 [inline]
 call_rcu+0xbb/0x700 kernel/rcu/tree.c:3038
 destroy_inode+0x129/0x1b0 fs/inode.c:288
 iput_final fs/inode.c:1653 [inline]
 iput.part.0+0x57e/0x810 fs/inode.c:1679
 iput+0x58/0x70 fs/inode.c:1669
 init_statfs fs/gfs2/ops_fstype.c:672 [inline]
 init_journal fs/gfs2/ops_fstype.c:788 [inline]
 init_inodes+0x19a7/0x2650 fs/gfs2/ops_fstype.c:857
 gfs2_fill_super+0x1ae8/0x2580 fs/gfs2/ops_fstype.c:1184
 get_tree_bdev+0x440/0x760 fs/super.c:1291
 gfs2_get_tree+0x4a/0x270 fs/gfs2/ops_fstype.c:1260
 vfs_get_tree+0x89/0x2f0 fs/super.c:1496
 do_new_mount fs/namespace.c:2878 [inline]
 path_mount+0x13ad/0x20c0 fs/namespace.c:3208
 do_mount fs/namespace.c:3221 [inline]
 __do_sys_mount fs/namespace.c:3429 [inline]
 __se_sys_mount fs/namespace.c:3406 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3406
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Second to last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xc5/0xf0 mm/kasan/generic.c:344
 __call_rcu kernel/rcu/tree.c:2965 [inline]
 call_rcu+0xbb/0x700 kernel/rcu/tree.c:3038
 destroy_inode+0x129/0x1b0 fs/inode.c:288
 iput_final fs/inode.c:1653 [inline]
 iput.part.0+0x57e/0x810 fs/inode.c:1679
 iput+0x58/0x70 fs/inode.c:1669
 init_statfs fs/gfs2/ops_fstype.c:672 [inline]
 init_journal fs/gfs2/ops_fstype.c:788 [inline]
 init_inodes+0x19a7/0x2650 fs/gfs2/ops_fstype.c:857
 gfs2_fill_super+0x1ae8/0x2580 fs/gfs2/ops_fstype.c:1184
 get_tree_bdev+0x440/0x760 fs/super.c:1291
 gfs2_get_tree+0x4a/0x270 fs/gfs2/ops_fstype.c:1260
 vfs_get_tree+0x89/0x2f0 fs/super.c:1496
 do_new_mount fs/namespace.c:2878 [inline]
 path_mount+0x13ad/0x20c0 fs/namespace.c:3208
 do_mount fs/namespace.c:3221 [inline]
 __do_sys_mount fs/namespace.c:3429 [inline]
 __se_sys_mount fs/namespace.c:3406 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3406
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8880929db380
 which belongs to the cache gfs2_inode of size 1520
The buggy address is located 216 bytes inside of
 1520-byte region [ffff8880929db380, ffff8880929db970)
The buggy address belongs to the page:
page:000000003726000d refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880929d8670 pfn:0x929d8
head:000000003726000d order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 ffffea0001e95400 0000000600000006 ffff88801709dc80
raw: ffff8880929d8670 0000000080130010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880929db300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880929db380: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880929db400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff8880929db480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880929db500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Maintainers
ci-upstream-kasan-gce-root	2021/01/16 23:32	upstream	1d94330a	65a7a854	.config	log	report			info	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-linux-next-kasan-gce-root	2020/11/18 19:26	linux-next	20529233	09323409	.config	log	report			info	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk