KASAN: use-after-free Read in bio_poll

Status: upstream: reported C repro on 2022/05/09 16:14
Fix commit: 9650b453a3d4 block: ignore RWF_HIPRI hint for sync dio
Patched on: [ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-leak ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce ci-upstream-kmsan-gce-386 ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-qemu2-riscv64]
First crash: 174d, last: 54d

Cause bisection: introduced by (bisect log) :
commit 0f38d76646157357fcfa02f50575ea044830c494
Author: Christoph Hellwig <>
Date: Tue Oct 12 10:40:45 2021 +0000

  blk-mq: cleanup blk_mq_submit_bio

Crash: general protection fault in hctx_lock (log)
Repro: C syz .config

Sample crash report:
BUG: KASAN: use-after-free in bio_poll+0x41/0x290 block/blk-core.c:941
Read of size 8 at addr ffff88807f015508 by task syz-executor237/3600

CPU: 0 PID: 3600 Comm: syz-executor237 Not tainted 5.18.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_address_description+0x65/0x4b0 mm/kasan/report.c:313
 print_report+0xf4/0x210 mm/kasan/report.c:429
 kasan_report+0xfb/0x130 mm/kasan/report.c:491
 bio_poll+0x41/0x290 block/blk-core.c:941
 __iomap_dio_rw+0x1a95/0x1ea0 fs/iomap/direct-io.c:658
 iomap_dio_rw+0x38/0x80 fs/iomap/direct-io.c:681
 ext4_dio_write_iter fs/ext4/file.c:566 [inline]
 ext4_file_write_iter+0x14fc/0x1960 fs/ext4/file.c:677
 do_iter_write+0x1f1/0x7a0 fs/read_write.c:852
 vfs_writev fs/read_write.c:925 [inline]
 do_pwritev+0x219/0x360 fs/read_write.c:1022
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
RIP: 0033:0x7f2d8b046e69
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 90 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:00007ffe6399e988 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 000000000000a252 RCX: 00007f2d8b046e69
RDX: 0000000000000001 RSI: 0000000020000240 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000003
R10: 0000000000001400 R11: 0000000000000246 R12: 00007ffe6399e9ac
R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the physical page:
page:ffffea0001fc0540 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7f015
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001eccac8 ffff8880b9b40038 0000000000000000
raw: 0000000000000000 00000000000c0000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x92800(GFP_NOWAIT|__GFP_NOWARN|__GFP_NORETRY|__GFP_NOMEMALLOC), pid 2931, tgid 2931 (jbd2/sda1-8), ts 18049756371, free_ts 41846633810
 prep_new_page mm/page_alloc.c:2441 [inline]
 get_page_from_freelist+0x72e/0x7a0 mm/page_alloc.c:4182
 __alloc_pages+0x26c/0x5f0 mm/page_alloc.c:5408
 alloc_slab_page+0x70/0xf0 mm/slub.c:1799
 allocate_slab+0x5e/0x560 mm/slub.c:1944
 new_slab mm/slub.c:2004 [inline]
 ___slab_alloc+0x41e/0xcd0 mm/slub.c:3005
 __slab_alloc mm/slub.c:3092 [inline]
 slab_alloc_node mm/slub.c:3183 [inline]
 slab_alloc mm/slub.c:3225 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3232 [inline]
 kmem_cache_alloc+0x246/0x2f0 mm/slub.c:3242
 mempool_alloc+0x17d/0x5c0 mm/mempool.c:392
 bio_alloc_bioset+0x144/0xce0 block/bio.c:492
 bio_alloc include/linux/bio.h:426 [inline]
 submit_bh_wbc+0x262/0x4e0 fs/buffer.c:3025
 submit_bh+0x1e/0x30 fs/buffer.c:3051
 jbd2_journal_commit_transaction+0x297d/0x5a80 fs/jbd2/commit.c:764
 kjournald2+0x4c4/0x950 fs/jbd2/journal.c:213
 kthread+0x266/0x300 kernel/kthread.c:376
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1356 [inline]
 free_pcp_prepare+0x812/0x900 mm/page_alloc.c:1406
 free_unref_page_prepare mm/page_alloc.c:3328 [inline]
 free_unref_page+0x7d/0x390 mm/page_alloc.c:3423
 rcu_do_batch kernel/rcu/tree.c:2535 [inline]
 rcu_core+0xa0c/0x16d0 kernel/rcu/tree.c:2786
 __do_softirq+0x382/0x793 kernel/softirq.c:558

Memory state around the buggy address:
 ffff88807f015400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88807f015480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88807f015500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88807f015580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88807f015600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff

Crashes (6):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-smack-root 2022/05/09 17:20 upstream c5eb0a61238d 8b277b8e .config log report syz C KASAN: use-after-free Read in bio_poll
ci-upstream-kasan-gce-root 2022/05/09 16:13 upstream c5eb0a61238d 8b277b8e .config log report syz C KASAN: use-after-free Read in bio_poll
ci-upstream-kasan-gce-root 2022/05/09 10:57 upstream c5eb0a61238d 8b277b8e .config log report info KASAN: use-after-free Read in bio_poll
ci-upstream-kasan-gce-smack-root 2022/01/09 22:49 upstream 4634129ad9fd 2ca0d385 .config log report info KASAN: use-after-free Read in bio_poll
ci-upstream-kasan-gce-smack-root 2022/05/09 14:57 upstream c5eb0a61238d 8b277b8e .config log report info general protection fault in bio_poll
ci-upstream-kasan-gce-selinux-root 2022/02/28 23:48 upstream 7e57714cd0ad 45a13a73 .config log report info KFENCE: use-after-free in bio_poll