syzbot


KASAN: use-after-free Read in ext4_rename_dir_prepare

Status: fixed on 2023/01/17 16:18
Reported-by: syzbot+a07b88e6427ec1c97aa5@syzkaller.appspotmail.com
Fix commit: dd887f83ea54 BACKPORT: ext4: fix use-after-free in ext4_rename_dir_prepare
First crash: 613d, last: 578d
Cause bisection: failed (error log, bisect log)
  
Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 KASAN: use-after-free Read in ext4_rename_dir_prepare C error 2 516d 612d 0/1 upstream: reported C repro on 2022/11/19 04:34
android-5-10 KASAN: use-after-free Read in ext4_rename_dir_prepare (3) C error 4 450d 450d 2/2 fixed on 2023/05/08 19:06
android-5-10 KASAN: use-after-free Read in ext4_rename_dir_prepare (2) C error inconclusive 3 516d 516d 2/2 fixed on 2023/03/28 17:56
Last patch testing requests (10)
Created Duration User Patch Repo Result
2022/12/27 07:41 19m tudor.ambarus@linaro.org https://github.com/ambarus/linux.git aa24193798a32d93b5a815ddf358a3aa83e7d94f OK log
2022/12/23 15:24 4m tudor.ambarus@linaro.org https://github.com/ambarus/linux.git 87a572e2765a35a8dc0c1c63133c3ae6075c0bb2 error
2022/12/23 15:17 0m tudor.ambarus@linaro.org https://android.googlesource.com/kernel/common syzkaller-id-851d58d972-android12-5.10 error
2022/12/23 15:02 4m tudor.ambarus@linaro.org https://github.com/ambarus/linux.git syzkaller-id-851d58d9728e1620971dc5d67a0865627d04b4d6 error
2022/12/23 07:10 7m tudor.ambarus@linaro.org android12-5.10-lts report log
2022/12/22 12:43 15m tudor.ambarus@linaro.org android13-5.10-lts OK log
2022/12/22 12:42 17m tudor.ambarus@linaro.org https://android.googlesource.com/kernel/common android13-5.10 OK log
2022/12/12 08:45 15m tudor.ambarus@linaro.org git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git linux-5.15.y OK log
2022/12/12 08:44 16m tudor.ambarus@linaro.org git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git linux-5.10.y OK log
2022/12/12 08:44 15m tudor.ambarus@linaro.org git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master OK log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in ext4_rename_dir_prepare+0x42e/0x4a0 fs/ext4/namei.c:3696
Read of size 4 at addr ffff8881025f0e02 by task syz-executor419/373

CPU: 0 PID: 373 Comm: syz-executor419 Not tainted 5.10.150-syzkaller-00396-g6b31c548a114 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118
 print_address_description+0x81/0x3c0 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report+0x1a4/0x1f0 mm/kasan/report.c:436
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 ext4_rename_dir_prepare+0x42e/0x4a0 fs/ext4/namei.c:3696
 ext4_cross_rename fs/ext4/namei.c:4204 [inline]
 ext4_rename2+0x1f37/0x45a0 fs/ext4/namei.c:4288
 vfs_rename+0x95e/0xde0 fs/namei.c:4389
 do_renameat2+0x83e/0x1190 fs/namei.c:4536
 __do_sys_renameat2 fs/namei.c:4571 [inline]
 __se_sys_renameat2 fs/namei.c:4568 [inline]
 __x64_sys_renameat2+0xbf/0xd0 fs/namei.c:4568
 do_syscall_64+0x34/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xc6
RIP: 0033:0x7f1442ba96f9
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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd85d268b8 EFLAGS: 00000246 ORIG_RAX: 000000000000013c
RAX: ffffffffffffffda RBX: 00007f1442beeec8 RCX: 00007f1442ba96f9
RDX: 00000000ffffff9c RSI: 00000000200004c0 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000002 R09: 00007ffd85d268e0
R10: 0000000020000000 R11: 0000000000000246 R12: 00007f1442b68590
R13: 00007ffd85d26910 R14: 00007ffd85d268f0 R15: 0000000000000000

Allocated by task 372:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:428 [inline]
 __kasan_slab_alloc+0xb2/0xe0 mm/kasan/common.c:461
 kasan_slab_alloc include/linux/kasan.h:259 [inline]
 slab_post_alloc_hook include/../mm/slab.h:583 [inline]
 slab_alloc_node mm/slub.c:2956 [inline]
 slab_alloc mm/slub.c:2964 [inline]
 kmem_cache_alloc+0x16c/0x300 mm/slub.c:2969
 mempool_alloc_slab+0x1d/0x30 mm/mempool.c:513
 mempool_alloc+0x135/0x530 mm/mempool.c:393
 bio_alloc_bioset+0x1db/0x650 block/bio.c:486
 bio_alloc include/linux/bio.h:407 [inline]
 mpage_alloc fs/mpage.c:115 [inline]
 do_mpage_readpage+0x14e6/0x1b50 fs/mpage.c:342
 mpage_readahead+0x2d5/0x5f0 fs/mpage.c:427
 blkdev_readahead+0x1c/0x20 fs/block_dev.c:651
 read_pages+0x160/0xb60 mm/readahead.c:140
 page_cache_ra_unbounded+0x6d0/0x8b0 mm/readahead.c:248
 do_page_cache_ra mm/readahead.c:277 [inline]
 force_page_cache_ra+0x3e6/0x440 mm/readahead.c:308
 page_cache_sync_ra+0x253/0x2c0 mm/readahead.c:584
 page_cache_sync_readahead include/linux/pagemap.h:837 [inline]
 generic_file_buffered_read+0x65f/0x2850 mm/filemap.c:2247
 generic_file_read_iter+0x106/0x6d0 mm/filemap.c:2565
 blkdev_read_iter+0x135/0x190 fs/block_dev.c:1954
 call_read_iter include/linux/fs.h:1946 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x9e2/0xbf0 fs/read_write.c:496
 ksys_read+0x198/0x2c0 fs/read_write.c:634
 __do_sys_read fs/read_write.c:644 [inline]
 __se_sys_read fs/read_write.c:642 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:642
 do_syscall_64+0x34/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xc6

Freed by task 12:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:46
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:357
 ____kasan_slab_free+0x121/0x160 mm/kasan/common.c:360
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:368
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:1604 [inline]
 slab_free_freelist_hook+0xcc/0x1a0 mm/slub.c:1630
 slab_free mm/slub.c:3212 [inline]
 kmem_cache_free+0xa9/0x1f0 mm/slub.c:3228
 mempool_free_slab+0x1d/0x30 mm/mempool.c:520
 mempool_free+0xd5/0x310 mm/mempool.c:502
 bio_put+0x34e/0x420 block/bio.c:266
 mpage_end_io+0x325/0x5b0 fs/mpage.c:76
 bio_endio+0x465/0x5c0 block/bio.c:1459
 req_bio_endio block/blk-core.c:269 [inline]
 blk_update_request+0x6d5/0x1250 block/blk-core.c:1471
 blk_mq_end_request+0x42/0x80 block/blk-mq.c:568
 lo_complete_rq+0x151/0x2e0 drivers/block/loop.c:488
 blk_done_softirq+0x372/0x410 block/blk-mq.c:592
 __do_softirq+0x27e/0x596 kernel/softirq.c:305

The buggy address belongs to the object at ffff8881025f0dc0
 which belongs to the cache bio-0 of size 216
The buggy address is located 66 bytes inside of
 216-byte region [ffff8881025f0dc0, ffff8881025f0e98)
The buggy address belongs to the page:
page:ffffea0004097c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1025f0
flags: 0x8000000000000200(slab)
raw: 8000000000000200 dead000000000100 dead000000000122 ffff888107fe8c00
raw: 0000000000000000 00000000800c000c 00000001ffffffff 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 0x92880(GFP_NOWAIT|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_NOMEMALLOC), pid 372, ts 19954386757, free_ts 19891007038
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2386 [inline]
 prep_new_page mm/page_alloc.c:2392 [inline]
 get_page_from_freelist+0x755/0x810 mm/page_alloc.c:4073
 __alloc_pages_nodemask+0x3b6/0x890 mm/page_alloc.c:5160
 alloc_slab_page mm/slub.c:1815 [inline]
 allocate_slab+0x78/0x540 mm/slub.c:1817
 new_slab mm/slub.c:1878 [inline]
 new_slab_objects mm/slub.c:2636 [inline]
 ___slab_alloc+0x131/0x2e0 mm/slub.c:2800
 __slab_alloc+0x63/0xa0 mm/slub.c:2840
 slab_alloc_node mm/slub.c:2922 [inline]
 slab_alloc mm/slub.c:2964 [inline]
 kmem_cache_alloc+0x1ef/0x300 mm/slub.c:2969
 mempool_alloc_slab+0x1d/0x30 mm/mempool.c:513
 mempool_alloc+0x135/0x530 mm/mempool.c:393
 bio_alloc_bioset+0x1db/0x650 block/bio.c:486
 bio_alloc include/linux/bio.h:407 [inline]
 mpage_alloc fs/mpage.c:115 [inline]
 do_mpage_readpage+0x14e6/0x1b50 fs/mpage.c:342
 mpage_readahead+0x2d5/0x5f0 fs/mpage.c:427
 blkdev_readahead+0x1c/0x20 fs/block_dev.c:651
 read_pages+0x160/0xb60 mm/readahead.c:140
 page_cache_ra_unbounded+0x6d0/0x8b0 mm/readahead.c:248
 do_page_cache_ra mm/readahead.c:277 [inline]
 force_page_cache_ra+0x3e6/0x440 mm/readahead.c:308
 page_cache_sync_ra+0x253/0x2c0 mm/readahead.c:584
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1332 [inline]
 free_pcp_prepare+0x18c/0x1c0 mm/page_alloc.c:1406
 free_unref_page_prepare mm/page_alloc.c:3293 [inline]
 free_unref_page_list+0x11d/0x660 mm/page_alloc.c:3367
 release_pages+0xc24/0xc60 mm/swap.c:1082
 __pagevec_release+0x81/0xf0 mm/swap.c:1102
 pagevec_release include/linux/pagevec.h:88 [inline]
 truncate_inode_pages_range+0x9f8/0x1940 mm/truncate.c:367
 truncate_inode_pages+0x24/0x30 mm/truncate.c:473
 kill_bdev fs/block_dev.c:86 [inline]
 set_blocksize+0x36e/0x3e0 fs/block_dev.c:171
 sb_set_blocksize fs/block_dev.c:180 [inline]
 sb_min_blocksize+0x101/0x1e0 fs/block_dev.c:196
 ext4_fill_super+0x757/0x9150 fs/ext4/super.c:4075
 mount_bdev+0x25f/0x370 fs/super.c:1419
 ext4_mount+0x34/0x40 fs/ext4/super.c:6606
 legacy_get_tree+0xf0/0x190 fs/fs_context.c:592
 vfs_get_tree+0x88/0x290 fs/super.c:1549
 do_new_mount+0x289/0xad0 fs/namespace.c:2899
 path_mount+0x58d/0xce0 fs/namespace.c:3229
 do_mount fs/namespace.c:3242 [inline]
 __do_sys_mount fs/namespace.c:3450 [inline]
 __se_sys_mount+0x2d2/0x3c0 fs/namespace.c:3427

Memory state around the buggy address:
 ffff8881025f0d00: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc
 ffff8881025f0d80: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
>ffff8881025f0e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8881025f0e80: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881025f0f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2022/11/18 09:02 android12-5.10-lts 6b31c548a114 5bb70014 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_rename_dir_prepare
2022/11/18 08:51 android12-5.10-lts 6b31c548a114 5bb70014 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_rename_dir_prepare
* Struck through repros no longer work on HEAD.