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

Status: upstream: reported C repro on 2025/05/11 21:42
Subsystems: netfs
[Documentation on labels]
Reported-by: syzbot+25b83a6f2c702075fcbc@syzkaller.appspotmail.com
Fix commit: 4481f7f2b3df netfs: Fix oops in write-retry from mis-resetting the subreq iterator
Patched on: [ci-qemu-gce-upstream-auto ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root 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-386-root ci-upstream-kmsan-gce-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-qemu-native-arm64-kvm]
First crash: 42d, last: 15d
▶ ▼ Discussions (3)
Title Replies (including bot) Last reply
[PATCH 6.15 453/780] netfs: Fix oops in write-retry from mis-resetting the subreq iterator 1 (1) 2025/06/17 15:22
[PATCH 1/4] netfs: Fix oops in write-retry from mis-resetting the subreq iterator 1 (1) 2025/05/19 09:07
[syzbot] [netfs?] KASAN: slab-out-of-bounds Read in iov_iter_revert 2 (5) 2025/05/16 22:58
▶ ▼ Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in iov_iter_revert fuse C done 325 43d 271d 0/29 closed as dup on 2025/01/02 21:12
upstream KASAN: stack-out-of-bounds Read in iov_iter_revert fs io-uring C error 14 1389d 1406d 20/29 fixed on 2021/11/10 00:50
linux-4.19 KASAN: stack-out-of-bounds Read in iov_iter_revert C error 26 874d 1433d 0/1 upstream: reported C repro on 2021/07/16 11:05
android-5-10 KASAN: stack-out-of-bounds Read in iov_iter_revert C error 10 1179d 1332d 0/2 closed as invalid on 2022/04/06 16:19
linux-4.14 KASAN: stack-out-of-bounds Read in iov_iter_revert xfs C error 8 872d 1375d 0/1 upstream: reported C repro on 2021/09/12 17:39
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/05/16 22:38 18m dhowells@redhat.com patch git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git v6.15-rc6 OK log

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in iov_iter_revert lib/iov_iter.c:633 [inline]
BUG: KASAN: slab-out-of-bounds in iov_iter_revert+0x443/0x5a0 lib/iov_iter.c:611
Read of size 4 at addr ffff88802912a0b8 by task kworker/u32:7/1147

CPU: 1 UID: 0 PID: 1147 Comm: kworker/u32:7 Not tainted 6.15.0-rc6-syzkaller-00052-g9f35e33144ae #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: events_unbound netfs_write_collection_worker
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xc3/0x670 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 iov_iter_revert lib/iov_iter.c:633 [inline]
 iov_iter_revert+0x443/0x5a0 lib/iov_iter.c:611
 netfs_retry_write_stream fs/netfs/write_retry.c:44 [inline]
 netfs_retry_writes+0x166d/0x1a50 fs/netfs/write_retry.c:231
 netfs_collect_write_results fs/netfs/write_collect.c:352 [inline]
 netfs_write_collection_worker+0x23fd/0x3830 fs/netfs/write_collect.c:374
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 5936:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_noprof+0x223/0x510 mm/slub.c:4339
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 tomoyo_encode2+0x100/0x3e0 security/tomoyo/realpath.c:45
 tomoyo_encode+0x29/0x50 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x18f/0x6e0 security/tomoyo/realpath.c:283
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x274/0x460 security/tomoyo/file.c:822
 security_file_truncate+0x84/0x1e0 security/security.c:3146
 handle_truncate fs/namei.c:3499 [inline]
 do_open fs/namei.c:3884 [inline]
 path_openat+0xc85/0x2d40 fs/namei.c:4039
 do_filp_open+0x20b/0x470 fs/namei.c:4066
 do_sys_openat2+0x11b/0x1d0 fs/open.c:1429
 do_sys_open fs/open.c:1444 [inline]
 __do_sys_creat fs/open.c:1522 [inline]
 __se_sys_creat fs/open.c:1516 [inline]
 __x64_sys_creat+0xcc/0x120 fs/open.c:1516
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5936:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2380 [inline]
 slab_free mm/slub.c:4642 [inline]
 kfree+0x2b6/0x4d0 mm/slub.c:4841
 tomoyo_path_perm+0x29a/0x460 security/tomoyo/file.c:842
 security_file_truncate+0x84/0x1e0 security/security.c:3146
 handle_truncate fs/namei.c:3499 [inline]
 do_open fs/namei.c:3884 [inline]
 path_openat+0xc85/0x2d40 fs/namei.c:4039
 do_filp_open+0x20b/0x470 fs/namei.c:4066
 do_sys_openat2+0x11b/0x1d0 fs/open.c:1429
 do_sys_open fs/open.c:1444 [inline]
 __do_sys_creat fs/open.c:1522 [inline]
 __se_sys_creat fs/open.c:1516 [inline]
 __x64_sys_creat+0xcc/0x120 fs/open.c:1516
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802912a0a0
 which belongs to the cache kmalloc-16 of size 16
The buggy address is located 8 bytes to the right of
 allocated 16-byte region [ffff88802912a0a0, ffff88802912a0b0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2912a
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801b442640 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080800080 00000000f5000000 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 0x52c00(GFP_NOIO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1, tgid 1 (swapper/0), ts 13358119373, free_ts 11984335158
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x181/0x1b0 mm/page_alloc.c:1718
 prep_new_page mm/page_alloc.c:1726 [inline]
 get_page_from_freelist+0x135c/0x3920 mm/page_alloc.c:3688
 __alloc_frozen_pages_noprof+0x263/0x23a0 mm/page_alloc.c:4970
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2301
 alloc_slab_page mm/slub.c:2450 [inline]
 allocate_slab mm/slub.c:2618 [inline]
 new_slab+0x244/0x340 mm/slub.c:2672
 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3858
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3948
 __slab_alloc_node mm/slub.c:4023 [inline]
 slab_alloc_node mm/slub.c:4184 [inline]
 __do_kmalloc_node mm/slub.c:4326 [inline]
 __kmalloc_noprof+0x2f2/0x510 mm/slub.c:4339
 kmalloc_noprof include/linux/slab.h:909 [inline]
 usb_cache_string+0xab/0x150 drivers/usb/core/message.c:1032
 usb_enumerate_device drivers/usb/core/hub.c:2508 [inline]
 usb_new_device+0x238/0x1a20 drivers/usb/core/hub.c:2633
 register_root_hub+0x299/0x730 drivers/usb/core/hcd.c:994
 usb_add_hcd+0xaf2/0x1730 drivers/usb/core/hcd.c:2976
 dummy_hcd_probe+0x15c/0x380 drivers/usb/gadget/udc/dummy_hcd.c:2693
 platform_probe+0x102/0x1f0 drivers/base/platform.c:1404
 call_driver_probe drivers/base/dd.c:579 [inline]
 really_probe+0x23e/0xa90 drivers/base/dd.c:657
 __driver_probe_device+0x1de/0x440 drivers/base/dd.c:799
page last free pid 838 tgid 838 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 __free_frozen_pages+0x69d/0xff0 mm/page_alloc.c:2725
 vfree+0x176/0x960 mm/vmalloc.c:3384
 delayed_vfree_work+0x56/0x70 mm/vmalloc.c:3304
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888029129f80: 00 02 fc fc 00 04 fc fc 00 04 fc fc 00 04 fc fc
 ffff88802912a000: 00 05 fc fc 00 00 fc fc 00 01 fc fc 00 01 fc fc
>ffff88802912a080: 00 01 fc fc fa fb fc fc 00 00 fc fc 00 05 fc fc
                                        ^
 ffff88802912a100: 00 01 fc fc fa fb fc fc fa fb fc fc 00 00 fc fc
 ffff88802912a180: 00 01 fc fc 00 00 fc fc 00 01 fc fc 00 01 fc fc
==================================================================

Crashes (30):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/14 13:04 upstream 9f35e33144ae a4fa04ef .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/05/31 02:58 upstream 8477ab143069 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/05/30 02:36 upstream e0797d3b91de 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/05/23 20:52 upstream eccf6f2f6ab9 f8cc0c83 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/05/20 17:44 upstream a5806cd506af 8f9cf946 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/05/17 23:39 upstream 172a9d94339c f41472b0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/05/14 02:48 upstream 405e6c37c89e 7344edeb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/05/13 10:08 upstream e9565e23cd89 f6671af7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/05/13 04:30 upstream 82f2b0b97b36 f6671af7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/05/12 22:36 upstream 82f2b0b97b36 f6671af7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/05/08 04:03 upstream d76bb1ebb558 dbf35fa1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/05/07 21:34 upstream 707df3375124 350f4ffc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/05/14 12:21 upstream 9f35e33144ae a4fa04ef .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-out-of-bounds Read in iov_iter_revert
2025/06/03 07:37 upstream 7f9039c524a3 b396b4bf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root general protection fault in iov_iter_revert
2025/06/01 04:29 upstream 4cb6c8af8591 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root general protection fault in iov_iter_revert
2025/05/31 14:37 upstream 0f70f5b08a47 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root general protection fault in iov_iter_revert
2025/05/25 10:12 upstream d0c22de9995b ed351ea7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root general protection fault in iov_iter_revert
2025/05/22 14:58 upstream d608703fcdd9 0919b50b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root general protection fault in iov_iter_revert
2025/05/17 12:21 upstream 172a9d94339c f41472b0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root general protection fault in iov_iter_revert
2025/05/16 19:07 upstream 3c21441eeffc cfde8269 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root general protection fault in iov_iter_revert
2025/05/14 00:50 upstream 405e6c37c89e 7344edeb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root general protection fault in iov_iter_revert
2025/05/12 07:04 upstream 82f2b0b97b36 77908e5f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root general protection fault in iov_iter_revert
2025/05/12 00:59 upstream cd802e7e5f1e 77908e5f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root general protection fault in iov_iter_revert
2025/05/11 12:22 upstream 3ce9925823c7 77908e5f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root general protection fault in iov_iter_revert
2025/05/10 12:40 upstream 0e1329d4045c 77908e5f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root general protection fault in iov_iter_revert
2025/05/10 01:14 upstream 3013c33dcbd9 bb813bcc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root general protection fault in iov_iter_revert
2025/05/27 09:28 upstream ddddf9d64f73 874a1386 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root general protection fault in iov_iter_revert
2025/05/18 14:16 upstream 5723cc3450bc f41472b0 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root general protection fault in iov_iter_revert
2025/05/24 14:42 upstream 4856ebd99715 ed351ea7 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 general protection fault in iov_iter_revert
2025/05/24 14:42 upstream 4856ebd99715 ed351ea7 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 general protection fault in iov_iter_revert
* Struck through repros no longer work on HEAD.