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KASAN: slab-use-after-free Read in ucma_create_uevent

Status: upstream: reported C repro on 2025/07/09 00:12
Subsystems: rdma
[Documentation on labels]
Reported-by: syzbot+a6ffe86390c8a6afc818@syzkaller.appspotmail.com
First crash: 316d, last: 11d
Cause bisection: failed (error log, bisect log)
  
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
82a542b6-8ec2-44a2-9ba8-098e3697f583 assessment-security 💥 KASAN: slab-use-after-free Read in ucma_create_uevent 2026/05/14 09:16 2026/05/14 09:16 2026/05/14 09:17 6ccb967e465e832a7bfd7a116ad00d52a0923a5d failed to run ["git" "pull" "origin" "HEAD" "--depth=1" "--allow-unrelated-histories"]: exit status 128 From /app/workdir/repo/linux * branch HEAD -> FETCH_HEAD Updating files: 29% (26273/89754) Updating files: 30% (26927/89754) Updating files: 31% (27824/89754) Updating files: 32% (28722/89754) Updating files: 33% (29619/89754) Updating files: 34% (30517/89754) Updating files: 35% (31414/89754) Updating files: 36% (32312/89754) Updating files: 37% (33209/89754) Updating files: 38% (34107/89754) Updating files: 39% (35005/89754) Updating files: 40% (35902/89754) Updating files: 40% (35925/89754) Updating files: 40% (36013/89754) error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_6_1_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_6_1_smn.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_0_default.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_0_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_0_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_0_smn.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_11_0_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_11_0_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_2_0_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_2_0_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_4_0_smn.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_4_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_4_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_7_0_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_7_0_sh_mask.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_9_0_offset.h error: unable to write file drivers/gpu/drm/amd/include/asic_reg/nbio/nbio_7_9_0_sh_mask.h fatal: cannot create directory at 'drivers/gpu/drm/amd/include/asic_reg/oss': No space left on device
▶ ▼ Discussions (7)
Title Replies (including bot) Last reply
[PATCH] RDMA/ucma: Fix use-after-free in ucma_create_uevent 2 (2) 2026/05/11 18:13
[syzbot] Monthly rdma report (Apr 2026) 0 (1) 2026/04/28 08:56
[syzbot] Monthly rdma report (Mar 2026) 0 (1) 2026/03/27 20:36
[syzbot] Monthly rdma report (Feb 2026) 0 (1) 2026/02/24 20:42
[syzbot] Monthly rdma report (Dec 2025) 0 (1) 2025/12/24 05:31
[syzbot] Monthly rdma report (Oct 2025) 1 (2) 2025/10/23 19:05
[syzbot] [rdma?] KASAN: slab-use-after-free Read in ucma_create_uevent 3 (9) 2025/07/26 01:50
▶ ▼ Last patch testing requests (15)
Created Duration User Patch Repo Result
2026/05/09 14:48 17m retest repro upstream report log
2026/03/20 18:31 3h56m retest repro linux-next report log
2026/03/06 16:05 13m retest repro upstream report log
2026/03/06 16:05 12m retest repro upstream report log
2026/02/20 14:59 13m retest repro upstream report log
2025/12/26 15:07 13m retest repro upstream report log
2025/12/26 14:58 29m retest repro linux-next report log
2025/12/26 15:07 14m retest repro upstream report log
2025/12/12 14:36 13m retest repro upstream report log
2025/10/17 14:35 13m retest repro upstream report log
2025/07/26 01:37 11m eadavis@qq.com patch upstream report log
2025/07/25 07:47 12m lizhi.xu@windriver.com patch upstream report log
2025/07/10 02:12 17m lizhi.xu@windriver.com patch upstream OK log
2025/07/09 02:27 11m eadavis@qq.com patch upstream report log
2025/07/09 02:06 49m hdanton@sina.com patch upstream OK log

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in ucma_create_uevent+0xadb/0xb30 drivers/infiniband/core/ucma.c:275
Read of size 8 at addr ffff888029155410 by task kworker/u32:9/1147

CPU: 3 UID: 0 PID: 1147 Comm: kworker/u32:9 Not tainted 6.16.0-rc5-syzkaller-00025-gd006330be3f7 #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: rdma_cm cma_iboe_join_work_handler
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+0xcd/0x680 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 ucma_create_uevent+0xadb/0xb30 drivers/infiniband/core/ucma.c:275
 ucma_event_handler+0x102/0x940 drivers/infiniband/core/ucma.c:351
 cma_cm_event_handler+0x97/0x300 drivers/infiniband/core/cma.c:2173
 cma_iboe_join_work_handler+0xca/0x170 drivers/infiniband/core/cma.c:3008
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3321 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 6107:
 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
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 ucma_process_join+0x237/0xa30 drivers/infiniband/core/ucma.c:1465
 ucma_join_multicast+0xe8/0x160 drivers/infiniband/core/ucma.c:1557
 ucma_write+0x1fb/0x330 drivers/infiniband/core/ucma.c:1738
 vfs_write+0x2a0/0x1150 fs/read_write.c:684
 ksys_write+0x1f8/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6107:
 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:2381 [inline]
 slab_free mm/slub.c:4643 [inline]
 kfree+0x2b4/0x4d0 mm/slub.c:4842
 ucma_process_join+0x3b9/0xa30 drivers/infiniband/core/ucma.c:1516
 ucma_join_multicast+0xe8/0x160 drivers/infiniband/core/ucma.c:1557
 ucma_write+0x1fb/0x330 drivers/infiniband/core/ucma.c:1738
 vfs_write+0x2a0/0x1150 fs/read_write.c:684
 ksys_write+0x1f8/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888029155400
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 16 bytes inside of
 freed 192-byte region [ffff888029155400, ffff8880291554c0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29155
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801b8423c0 ffffea0000a60c80 dead000000000002
raw: 0000000000000000 0000000080100010 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 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1, tgid 1 (swapper/0), ts 12897812541, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab mm/slub.c:2619 [inline]
 new_slab+0x23b/0x330 mm/slub.c:2673
 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3859
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949
 __slab_alloc_node mm/slub.c:4024 [inline]
 slab_alloc_node mm/slub.c:4185 [inline]
 __kmalloc_cache_noprof+0xfb/0x3e0 mm/slub.c:4354
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 call_usermodehelper_setup+0xaf/0x360 kernel/umh.c:362
 kobject_uevent_env+0x1690/0x1870 lib/kobject_uevent.c:628
 driver_bound+0x164/0x230 drivers/base/dd.c:421
 really_probe+0x62b/0xa90 drivers/base/dd.c:707
 __driver_probe_device+0x1de/0x440 drivers/base/dd.c:799
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:829
 __device_attach_driver+0x1df/0x310 drivers/base/dd.c:957
 bus_for_each_drv+0x156/0x1e0 drivers/base/bus.c:462
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888029155300: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888029155380: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888029155400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888029155480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888029155500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/08 19:52 upstream d006330be3f7 4d9fdfa4 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in ucma_create_uevent
2025/07/08 19:14 upstream d006330be3f7 4d9fdfa4 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in ucma_create_uevent
2025/07/08 18:34 upstream d006330be3f7 4d9fdfa4 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in ucma_create_uevent
2026/04/25 14:43 linux-next 7080e32d3f09 9c2d0995 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in ucma_create_uevent
2025/07/11 13:34 linux-next a62b7a37e6fc 3cda49cf .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in ucma_create_uevent
2025/07/08 17:59 upstream d006330be3f7 4d9fdfa4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in ucma_create_uevent
* Struck through repros no longer work on HEAD.