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KASAN: use-after-free Read in ext4_find_extent

Status: upstream: reported C repro on 2022/12/26 07:59
Labels: ext4 origin:lts (incorrect?)
Reported-by: syzbot+0827b4b52b5ebf65f219@syzkaller.appspotmail.com
First crash: 185d, last: 7d00h

Cause bisection: failed (error log, bisect log)
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[PATCH v2] ext4: Fix possible use-after-free in ext4_find_extent 6 (6) 2023/01/02 05:41
[PATCH] ext4: Fix possible use-after-free in ext4_find_extent 2 (2) 2022/12/29 22:40
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2023/05/05 lts (merge base) d86dfc4d95cd C [report] KASAN: use-after-free Read in ext4_find_extent
2023/05/05 upstream (ToT) 3c4aa4434377 C Didn't crash
▶ ▼ Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 KASAN: use-after-free Read in ext4_find_extent ext4 C error inconclusive 18 17d 164d 0/2 upstream: reported C repro on 2022/12/26 07:59
android-6-1 KASAN: use-after-free Read in ext4_find_extent 1 7d00h 7d00h 0/2 premoderation: reported on 2023/06/01 08:27
upstream KASAN: use-after-free Read in ext4_find_extent 2 596d 656d 0/24 auto-closed as invalid on 2022/02/17 05:19
upstream KASAN: use-after-free Read in ext4_find_extent (2) ext4 C error 2 34d 159d 23/24 upstream: reported C repro on 2022/12/31 07:08
android-54 KASAN: slab-out-of-bounds Read in ext4_find_extent ext4 C 1 48d 164d 0/2 upstream: reported C repro on 2022/12/26 07:49
▶ ▼ Last patch testing requests (3)
Created Duration User Patch Repo Result
2022/12/28 14:25 13m tudor.ambarus@linaro.org https://github.com/ambarus/linux.git 5ee4e1b578324fdfde35eaf5ceb30a19336c97f6 OK log
2022/12/28 13:48 7m tudor.ambarus@linaro.org upstream report log
2022/12/28 13:47 13m tudor.ambarus@linaro.org https://github.com/ambarus/linux.git f3c76c42a554367d313d2e315676b19535089ac3 OK log
▶ ▼ Fix bisection attempts (4)
Created Duration User Patch Repo Result
2023/06/01 08:00 16m bisect fix android13-5.15-lts job log (0) log
2023/05/01 12:38 18m bisect fix android13-5.15-lts job log (0) log
2023/03/04 00:47 18m bisect fix android13-5.15-lts job log (0) log
2023/02/01 21:22 28m bisect fix android13-5.15-lts job log (0) log

Sample crash report:
EXT4-fs error (device loop0): __ext4_get_inode_loc:4347: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbab/0xdb0 fs/ext4/extents.c:946
Read of size 4 at addr ffff88811e57e058 by task kworker/u4:1/10

CPU: 1 PID: 10 Comm: kworker/u4:1 Not tainted 5.15.98-syzkaller-00348-g7364b7abbafb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106
 print_address_description+0x87/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0x179/0x1c0 mm/kasan/report.c:444
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
 ext4_find_extent+0xbab/0xdb0 fs/ext4/extents.c:946
 ext4_ext_map_blocks+0x254/0x7250 fs/ext4/extents.c:4103
 ext4_map_blocks+0xaa7/0x1e30 fs/ext4/inode.c:646
 mpage_map_one_extent fs/ext4/inode.c:2419 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2472 [inline]
 ext4_writepages+0x162a/0x4010 fs/ext4/inode.c:2840
 do_writepages+0x40e/0x670 mm/page-writeback.c:2366
 __writeback_single_inode+0xdf/0xa70 fs/fs-writeback.c:1622
 writeback_sb_inodes+0xb2e/0x1910 fs/fs-writeback.c:1905
 wb_writeback+0x3b9/0x9e0 fs/fs-writeback.c:2079
 wb_do_writeback fs/fs-writeback.c:2222 [inline]
 wb_workfn+0x3d9/0x1110 fs/fs-writeback.c:2263
 process_one_work+0x6bb/0xc10 kernel/workqueue.c:2313
 worker_thread+0xad5/0x12a0 kernel/workqueue.c:2460
 kthread+0x421/0x510 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 <unknown>:298
 </TASK>

The buggy address belongs to the page:
page:ffffea0004795f80 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x11e57e
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea0004795fc8 ffffea00043663c8 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x101cca(GFP_HIGHUSER_MOVABLE|__GFP_WRITE), pid 322, ts 18363426224, free_ts 18363519432
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1a3/0x1b0 mm/page_alloc.c:2502
 prep_new_page mm/page_alloc.c:2508 [inline]
 get_page_from_freelist+0x2c14/0x2cf0 mm/page_alloc.c:4291
 __alloc_pages+0x386/0x7b0 mm/page_alloc.c:5569
 __alloc_pages_node include/linux/gfp.h:591 [inline]
 alloc_pages_node include/linux/gfp.h:605 [inline]
 alloc_pages include/linux/gfp.h:618 [inline]
 __page_cache_alloc include/linux/pagemap.h:305 [inline]
 pagecache_get_page+0xb18/0xeb0 mm/filemap.c:1940
 grab_cache_page_write_begin+0x5d/0xa0 mm/filemap.c:3785
 ext4_write_begin+0x29d/0x13d0 fs/ext4/inode.c:1194
 ext4_da_write_begin+0x4a2/0xc30 fs/ext4/inode.c:2986
 generic_perform_write+0x2bc/0x5a0 mm/filemap.c:3831
 ext4_buffered_write_iter+0x49c/0x630 fs/ext4/file.c:271
 ext4_file_write_iter+0x443/0x1cc0
 call_write_iter include/linux/fs.h:2157 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0xd8a/0x1160 fs/read_write.c:594
 ksys_write+0x199/0x2c0 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:656
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1370 [inline]
 free_pcp_prepare mm/page_alloc.c:1442 [inline]
 free_unref_page_prepare+0x7c8/0x7d0 mm/page_alloc.c:3441
 free_unref_page+0xac/0x2c0 mm/page_alloc.c:3521
 __put_single_page mm/swap.c:98 [inline]
 __put_page+0xb0/0xe0 mm/swap.c:129
 put_page include/linux/mm.h:1295 [inline]
 ext4_write_begin+0xfb2/0x13d0 fs/ext4/inode.c:1276
 ext4_da_write_begin+0x4a2/0xc30 fs/ext4/inode.c:2986
 generic_perform_write+0x2bc/0x5a0 mm/filemap.c:3831
 ext4_buffered_write_iter+0x49c/0x630 fs/ext4/file.c:271
 ext4_file_write_iter+0x443/0x1cc0
 call_write_iter include/linux/fs.h:2157 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0xd8a/0x1160 fs/read_write.c:594
 ksys_write+0x199/0x2c0 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:656
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff88811e57df00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88811e57df80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88811e57e000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                    ^
 ffff88811e57e080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88811e57e100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
------------[ cut here ]------------
kernel BUG at fs/ext4/inode.c:2431!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 10 Comm: kworker/u4:1 Tainted: G    B             5.15.98-syzkaller-00348-g7364b7abbafb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Workqueue: writeback wb_workfn (flush-7:0)
RIP: 0010:mpage_map_one_extent fs/ext4/inode.c:2431 [inline]
RIP: 0010:mpage_map_and_submit_extent fs/ext4/inode.c:2472 [inline]
RIP: 0010:ext4_writepages+0x3f45/0x4010 fs/ext4/inode.c:2840
Code: 00 74 08 48 89 df e8 0a f8 c9 ff 48 8b 3b 48 8b 74 24 48 48 8b 54 24 28 44 89 e9 45 89 f8 e8 82 42 08 00 eb 60 e8 3b c5 88 ff <0f> 0b e8 34 c5 88 ff eb 3b e8 2d c5 88 ff eb 7a e8 26 c5 88 ff 31
RSP: 0018:ffffc900000a7000 EFLAGS: 00010293
RAX: ffffffff81e69aa5 RBX: dffffc0000000000 RCX: ffff8881002593c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900000a7410 R08: ffffffff81e6746d R09: ffffed102203e024
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000000
R13: ffffc900000a72e0 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f909ee45508 CR3: 000000000660f000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 do_writepages+0x40e/0x670 mm/page-writeback.c:2366
 __writeback_single_inode+0xdf/0xa70 fs/fs-writeback.c:1622
 writeback_sb_inodes+0xb2e/0x1910 fs/fs-writeback.c:1905
 wb_writeback+0x3b9/0x9e0 fs/fs-writeback.c:2079
 wb_do_writeback fs/fs-writeback.c:2222 [inline]
 wb_workfn+0x3d9/0x1110 fs/fs-writeback.c:2263
 process_one_work+0x6bb/0xc10 kernel/workqueue.c:2313
 worker_thread+0xad5/0x12a0 kernel/workqueue.c:2460
 kthread+0x421/0x510 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 <unknown>:298
 </TASK>
Modules linked in:
---[ end trace b68c083357dd2f44 ]---
RIP: 0010:mpage_map_one_extent fs/ext4/inode.c:2431 [inline]
RIP: 0010:mpage_map_and_submit_extent fs/ext4/inode.c:2472 [inline]
RIP: 0010:ext4_writepages+0x3f45/0x4010 fs/ext4/inode.c:2840
Code: 00 74 08 48 89 df e8 0a f8 c9 ff 48 8b 3b 48 8b 74 24 48 48 8b 54 24 28 44 89 e9 45 89 f8 e8 82 42 08 00 eb 60 e8 3b c5 88 ff <0f> 0b e8 34 c5 88 ff eb 3b e8 2d c5 88 ff eb 7a e8 26 c5 88 ff 31
RSP: 0018:ffffc900000a7000 EFLAGS: 00010293
RAX: ffffffff81e69aa5 RBX: dffffc0000000000 RCX: ffff8881002593c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900000a7410 R08: ffffffff81e6746d R09: ffffed102203e024
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000000
R13: ffffc900000a72e0 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f909ee45508 CR3: 000000010b8f2000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Manager Title
2023/04/01 06:28 android13-5.15-lts 7364b7abbafb f325deb0 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-15 KASAN: use-after-free Read in ext4_find_extent
2023/03/19 02:20 android13-5.15-lts 5448b2fda85f 7939252e .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-15 KASAN: use-after-free Read in ext4_find_extent
2022/12/26 07:49 android13-5.15-lts c73b4619ad86 9da18ae8 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-15 KASAN: use-after-free Read in ext4_find_extent
2022/12/14 02:48 android13-5.15-lts 7048384c9872 f6511626 .config strace log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-15 KASAN: use-after-free Read in ext4_find_extent
2022/12/12 18:12 android13-5.15-lts 7048384c9872 67be1ae7 .config strace log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-15 KASAN: use-after-free Read in ext4_find_extent
2022/12/04 17:22 android13-5.15-lts 92f701cae0bc e080de16 .config strace log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-15 KASAN: use-after-free Read in ext4_find_extent
* Struck through repros no longer work on HEAD.