KASAN: slab-out-of-bounds Read in atomic_ptr_type_ok

Status: fixed on 2025/06/10 16:19
Subsystems: bpf
[Documentation on labels]
Reported-by: syzbot+a5964227adc0f904549c@syzkaller.appspotmail.com
Fix commit: 9aa8fe29f624 Merge branch 'bpf-fix-oob-read-and-add-tests-for-load-acquire-store-release' c03bb2fa327e bpf: Fix out-of-bounds read in check_atomic_load/store()
First crash: 503d, last: 503d
Cause bisection: introduced by (bisect log) :
commit e24bbad29a8de70bb33c1cabc85bb40e6707572a
Author: Peilin Ye <yepeilin@google.com>
Date: Tue Mar 4 01:06:13 2025 +0000

  bpf: Introduce load-acquire and store-release instructions

Crash: KASAN: slab-out-of-bounds Read in do_check (log)
Repro: C syz .config
  
▶ ▼ Discussions (4)
Title Replies (including bot) Last reply
[PATCH v3 bpf-next 0/2] bpf: Fix OOB read and add tests for load-acquire/store-release 4 (4) 2025/03/22 13:30
[PATCH v2 bpf-next 0/2] bpf: Fix OOB read and add tests for load-acquire/store-release 4 (4) 2025/03/21 22:16
[PATCH bpf-next v1] bpf: Fix out-of-bounds read in check_atomic_load/store() 4 (4) 2025/03/15 12:59
[syzbot] [bpf?] KASAN: slab-out-of-bounds Read in atomic_ptr_type_ok 3 (7) 2025/03/15 06:27
▶ ▼ Last patch testing requests (3)
Created Duration User Patch Repo Result
2025/03/15 06:00 26m enjuk@amazon.com patch bpf-next OK log
2025/03/15 05:11 10m enjuk@amazon.com patch bpf-next error
2025/03/14 18:19 26m enjuk@amazon.com patch bpf-next OK log

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in is_ctx_reg kernel/bpf/verifier.c:6185 [inline]
BUG: KASAN: slab-out-of-bounds in atomic_ptr_type_ok+0x3d7/0x550 kernel/bpf/verifier.c:6223
Read of size 4 at addr ffff888141b0d690 by task syz-executor143/5842

CPU: 1 UID: 0 PID: 5842 Comm: syz-executor143 Not tainted 6.14.0-rc3-syzkaller-gf28214603dc6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0x16e/0x5b0 mm/kasan/report.c:521
 kasan_report+0x143/0x180 mm/kasan/report.c:634
 is_ctx_reg kernel/bpf/verifier.c:6185 [inline]
 atomic_ptr_type_ok+0x3d7/0x550 kernel/bpf/verifier.c:6223
 check_atomic_store kernel/bpf/verifier.c:7804 [inline]
 check_atomic kernel/bpf/verifier.c:7841 [inline]
 do_check+0x89dd/0xedd0 kernel/bpf/verifier.c:19334
 do_check_common+0x1678/0x2080 kernel/bpf/verifier.c:22600
 do_check_main kernel/bpf/verifier.c:22691 [inline]
 bpf_check+0x165c8/0x1cca0 kernel/bpf/verifier.c:23821
 bpf_prog_load+0x1664/0x20e0 kernel/bpf/syscall.c:2967
 __sys_bpf+0x4ea/0x820 kernel/bpf/syscall.c:5811
 __do_sys_bpf kernel/bpf/syscall.c:5918 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5916 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5916
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa3ac86bab9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe50fff5f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fa3ac86bab9
RDX: 0000000000000094 RSI: 00004000000009c0 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000006
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001
 </TASK>

Allocated by task 5842:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __kmalloc_cache_noprof+0x243/0x390 mm/slub.c:4325
 kmalloc_noprof include/linux/slab.h:901 [inline]
 kzalloc_noprof include/linux/slab.h:1037 [inline]
 do_check_common+0x1ec/0x2080 kernel/bpf/verifier.c:22499
 do_check_main kernel/bpf/verifier.c:22691 [inline]
 bpf_check+0x165c8/0x1cca0 kernel/bpf/verifier.c:23821
 bpf_prog_load+0x1664/0x20e0 kernel/bpf/syscall.c:2967
 __sys_bpf+0x4ea/0x820 kernel/bpf/syscall.c:5811
 __do_sys_bpf kernel/bpf/syscall.c:5918 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5916 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5916
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888141b0d000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 312 bytes to the right of
 allocated 1368-byte region [ffff888141b0d000, ffff888141b0d558)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x141b08
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88801b042000 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff88801b042000 dead000000000100 dead000000000122
head: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000
head: 057ff00000000003 ffffea000506c201 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 8909973200, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1585
 prep_new_page mm/page_alloc.c:1593 [inline]
 get_page_from_freelist+0x3a8c/0x3c20 mm/page_alloc.c:3538
 __alloc_frozen_pages_noprof+0x264/0x580 mm/page_alloc.c:4805
 alloc_pages_mpol+0x311/0x660 mm/mempolicy.c:2270
 alloc_slab_page mm/slub.c:2423 [inline]
 allocate_slab+0x8f/0x3a0 mm/slub.c:2587
 new_slab mm/slub.c:2640 [inline]
 ___slab_alloc+0xc27/0x14a0 mm/slub.c:3826
 __slab_alloc+0x58/0xa0 mm/slub.c:3916
 __slab_alloc_node mm/slub.c:3991 [inline]
 slab_alloc_node mm/slub.c:4152 [inline]
 __kmalloc_cache_noprof+0x27b/0x390 mm/slub.c:4320
 kmalloc_noprof include/linux/slab.h:901 [inline]
 kzalloc_noprof include/linux/slab.h:1037 [inline]
 virtio_pci_probe+0x54/0x340 drivers/virtio/virtio_pci_common.c:689
 local_pci_probe drivers/pci/pci-driver.c:324 [inline]
 pci_call_probe drivers/pci/pci-driver.c:392 [inline]
 __pci_device_probe drivers/pci/pci-driver.c:417 [inline]
 pci_device_probe+0x6c5/0xa10 drivers/pci/pci-driver.c:451
 really_probe+0x2b9/0xad0 drivers/base/dd.c:658
 __driver_probe_device+0x1a2/0x390 drivers/base/dd.c:800
 driver_probe_device+0x50/0x430 drivers/base/dd.c:830
 __driver_attach+0x45f/0x710 drivers/base/dd.c:1216
 bus_for_each_dev+0x239/0x2b0 drivers/base/bus.c:370
 bus_add_driver+0x346/0x670 drivers/base/bus.c:678
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888141b0d580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888141b0d600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888141b0d680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff888141b0d700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888141b0d780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/03/09 18:20 bpf-next f28214603dc6 163f510d .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce KASAN: slab-out-of-bounds Read in atomic_ptr_type_ok
2025/03/09 17:50 bpf-next f28214603dc6 163f510d .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce KASAN: slab-out-of-bounds Read in atomic_ptr_type_ok
2025/03/09 17:22 bpf-next f28214603dc6 163f510d .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce KASAN: slab-out-of-bounds Read in atomic_ptr_type_ok
2025/03/09 16:50 bpf-next f28214603dc6 163f510d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce KASAN: slab-out-of-bounds Read in atomic_ptr_type_ok
* Struck through repros no longer work on HEAD.