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006d021491bc7-68be7de9730mr6588190eaf.30.1776225242393; Tue, 14 Apr 2026 20:54:02 -0700 (PDT) Date: Tue, 14 Apr 2026 20:54:02 -0700 In-Reply-To: <20260415003322.1854-1-hdanton@sina.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69df0bda.a00a0220.468cb.006f.GAE@google.com> Subject: Re: [syzbot] [dri?] KASAN: slab-use-after-free Read in drm_gem_object_release_handle From: syzbot To: hdanton@sina.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: KASAN: slab-use-after-free Read in drm_gem_object_release_handle ================================================================== BUG: KASAN: slab-use-after-free in drm_gem_object_release_handle+0x47/0x1e0 drivers/gpu/drm/drm_gem.c:374 Read of size 8 at addr ffff88802868ba78 by task syz.4.82/6783 CPU: 0 UID: 0 PID: 6783 Comm: syz.4.82 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xba/0x230 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 drm_gem_object_release_handle+0x47/0x1e0 drivers/gpu/drm/drm_gem.c:374 drm_gem_release+0xd2/0x170 drivers/gpu/drm/drm_gem.c:1096 drm_file_free+0x729/0xa00 drivers/gpu/drm/drm_file.c:261 drm_close_helper drivers/gpu/drm/drm_file.c:290 [inline] drm_release+0x2de/0x3f0 drivers/gpu/drm/drm_file.c:438 __fput+0x44f/0xa60 fs/file_table.c:510 task_work_run+0x1d9/0x270 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:328 [inline] do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7a5259c819 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff2b485db8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007f7a52817da0 RCX: 00007f7a5259c819 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f7a52817da0 R08: 00007f7a52816038 R09: 0000000000000000 R10: 000000000003fdc0 R11: 0000000000000246 R12: 000000000002456b R13: 00007f7a5281609c R14: 000000000002426f R15: 00007f7a52816090 Allocated by task 6785: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5380 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] __drm_gem_shmem_create+0xc4/0x2e0 drivers/gpu/drm/drm_gem_shmem_helper.c:130 drm_gem_shmem_create drivers/gpu/drm/drm_gem_shmem_helper.c:157 [inline] drm_gem_shmem_create_with_handle drivers/gpu/drm/drm_gem_shmem_helper.c:460 [inline] drm_gem_shmem_dumb_create+0x72/0x120 drivers/gpu/drm/drm_gem_shmem_helper.c:549 drm_mode_create_dumb drivers/gpu/drm/drm_dumb_buffers.c:227 [inline] drm_mode_create_dumb_ioctl+0x2bd/0x340 drivers/gpu/drm/drm_dumb_buffers.c:236 drm_ioctl_kernel+0x2df/0x3b0 drivers/gpu/drm/drm_ioctl.c:804 drm_ioctl+0x6ba/0xb80 drivers/gpu/drm/drm_ioctl.c:901 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 6785: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2685 [inline] slab_free mm/slub.c:6165 [inline] kfree+0x1c1/0x620 mm/slub.c:6483 drm_gem_object_free drivers/gpu/drm/drm_gem.c:1138 [inline] kref_put include/linux/kref.h:65 [inline] __drm_gem_object_put include/drm/drm_gem.h:565 [inline] drm_gem_object_put include/drm/drm_gem.h:578 [inline] drm_gem_change_handle_ioctl+0x392/0x4d0 drivers/gpu/drm/drm_gem.c:1052 drm_ioctl_kernel+0x2df/0x3b0 drivers/gpu/drm/drm_ioctl.c:804 drm_ioctl+0x6ba/0xb80 drivers/gpu/drm/drm_ioctl.c:901 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88802868b800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 632 bytes inside of freed 1024-byte region [ffff88802868b800, ffff88802868bc00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x28688 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88813fe2cdc0 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88813fe2cdc0 dead000000000100 dead000000000122 head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 00fff00000000003 ffffea0000a1a201 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2000(__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 69, tgid 69 (kworker/u8:4), ts 7935238695, free_ts 0 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889 prep_new_page mm/page_alloc.c:1897 [inline] get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250 alloc_slab_page mm/slub.c:3292 [inline] allocate_slab+0x77/0x660 mm/slub.c:3481 new_slab mm/slub.c:3539 [inline] refill_objects+0x331/0x3c0 mm/slub.c:7175 refill_sheaf mm/slub.c:2812 [inline] __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615 alloc_from_pcs mm/slub.c:4717 [inline] slab_alloc_node mm/slub.c:4851 [inline] __do_kmalloc_node mm/slub.c:5259 [inline] __kmalloc_node_noprof+0x577/0x7c0 mm/slub.c:5266 kmalloc_node_noprof include/linux/slab.h:1081 [inline] blk_alloc_flush_queue+0xe2/0x230 block/blk-flush.c:492 blk_mq_init_hctx block/blk-mq.c:4019 [inline] blk_mq_alloc_and_init_hctx+0x79e/0xc50 block/blk-mq.c:4558 __blk_mq_realloc_hw_ctxs+0x2bd/0x670 block/blk-mq.c:4605 blk_mq_realloc_hw_ctxs block/blk-mq.c:4642 [inline] blk_mq_init_allocated_queue+0x365/0x13e0 block/blk-mq.c:4672 blk_mq_alloc_queue+0x1ba/0x2e0 block/blk-mq.c:4454 scsi_alloc_sdev+0x7c0/0xc80 drivers/scsi/scsi_scan.c:339 scsi_probe_and_add_lun+0x200/0x4830 drivers/scsi/scsi_scan.c:1215 __scsi_scan_target+0x1f0/0xe10 drivers/scsi/scsi_scan.c:1786 scsi_scan_channel drivers/scsi/scsi_scan.c:1874 [inline] scsi_scan_host_selected+0x372/0x690 drivers/scsi/scsi_scan.c:1903 page_owner free stack trace missing Memory state around the buggy address: ffff88802868b900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88802868b980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88802868ba00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88802868ba80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88802868bb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Tested on: commit: 91a4855d Merge tag 'net-next-7.1' of git://git.kernel... git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1079fb02580000 kernel config: https://syzkaller.appspot.com/x/.config?x=95729ed00549063a dashboard link: https://syzkaller.appspot.com/bug?extid=b2e951687503f32f74ce compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 patch: https://syzkaller.appspot.com/x/patch.diff?x=112238ce580000