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2002:a05:6820:1613:b0:6b1:a8b3:3b43 with SMTP id 006d021491bc7-6b6fd7d71c3mr21413292eaf.24.1788987781967; Wed, 09 Sep 2026 14:03:01 -0700 (PDT) Date: Wed, 09 Sep 2026 14:03:01 -0700 In-Reply-To: <20260909202914.275119-1-user@adriano> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6aa1c985.f81106d8.2ab401.0000.GAE@google.com> Subject: Re: [syzbot] [serial?] KASAN: slab-use-after-free Write in release_tty From: syzbot To: adrianox@gmail.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 gs_close ================================================================== BUG: KASAN: slab-use-after-free in rt_spin_lock+0x83/0x40 kernel/locking/spinlock_rt.c:56 BUG: KASAN: slab-use-after-free in rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56 Read of size 1 at addr ffff88802b714488 by task syz-executor158/7333 CPU: 1 UID: 0 PID: 7333 Comm: syz-executor158 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description+0x55/0x1e0 mm/kasan/report.c:378 print_report+0x58/0x70 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 __kasan_check_byte+0x2a/0x40 mm/kasan/common.c:574 kasan_check_byte include/linux/kasan.h:402 [inline] lock_acquire+0x7d/0x350 kernel/locking/lockdep.c:5916 rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56 spin_lock_irq include/linux/spinlock_rt.h:96 [inline] gs_close+0xb9/0xbb0 drivers/usb/gadget/function/u_serial.c:698 tty_release+0x35f/0x1680 drivers/tty/tty_io.c:1718 __fput+0x42a/0xa80 fs/file_table.c:512 fput_close_sync+0x11f/0x240 fs/file_table.c:617 __do_sys_close fs/open.c:1560 [inline] __se_sys_close fs/open.c:1545 [inline] __x64_sys_close+0x7e/0x110 fs/open.c:1545 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fccd3f6ec0e Code: 08 0f 85 65 e1 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08 RSP: 002b:00007ffed8338a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: ffffffffffffffda RBX: 000055556cea1400 RCX: 00007fccd3f6ec0e RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000008 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000083a90 R13: 0000000000083ac2 R14: 00007fccd400bb2c R15: 00007fccd400bb20 Allocated by task 7334: 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+0x3d5/0x680 mm/slub.c:5563 _kmalloc_noprof include/linux/slab.h:991 [inline] _kzalloc_noprof include/linux/slab.h:1312 [inline] gs_port_alloc drivers/usb/gadget/function/u_serial.c:1264 [inline] gserial_alloc_line_no_console+0x23a/0x700 drivers/usb/gadget/function/u_serial.c:1349 gserial_alloc_line+0x18/0x90 drivers/usb/gadget/function/u_serial.c:1383 acm_alloc_instance+0xc7/0x140 drivers/usb/gadget/function/f_acm.c:891 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline] usb_get_function_instance+0xe3/0x2f0 drivers/usb/gadget/functions.c:44 function_make+0x127/0x360 drivers/usb/gadget/configfs.c:626 configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1369 vfs_mkdir+0x408/0x620 fs/namei.c:5410 filename_mkdirat+0x289/0x520 fs/namei.c:5443 __do_sys_mkdirat fs/namei.c:5464 [inline] __se_sys_mkdirat+0x35/0x150 fs/namei.c:5461 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 7334: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x40/0x50 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:2748 [inline] slab_free mm/slub.c:6499 [inline] kfree+0x1c5/0x6d0 mm/slub.c:6792 gserial_free_port+0x240/0x2c0 drivers/usb/gadget/function/u_serial.c:1313 gserial_free_line+0xc3/0x1f0 drivers/usb/gadget/function/u_serial.c:1330 acm_free_instance+0x39/0x60 drivers/usb/gadget/function/f_acm.c:875 usb_put_function_instance+0x95/0xc0 drivers/usb/gadget/functions.c:77 config_item_cleanup fs/configfs/item.c:128 [inline] config_item_release+0x13a/0x2d0 fs/configfs/item.c:137 configfs_rmdir+0x885/0x950 fs/configfs/dir.c:1580 vfs_rmdir+0x3e9/0x6b0 fs/namei.c:5515 filename_rmdir+0x292/0x520 fs/namei.c:5572 __do_sys_rmdir fs/namei.c:5595 [inline] __se_sys_rmdir+0x2e/0x140 fs/namei.c:5592 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88802b714000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 1160 bytes inside of freed 2048-byte region [ffff88802b714000, ffff88802b714800) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2b710 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x80000000000040(head|node=0|zone=1) page_type: f5(slab) raw: 0080000000000040 ffff88813ff00000 dead000000000100 dead000000000122 raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000 head: 0080000000000040 ffff88813ff00000 dead000000000100 dead000000000122 head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000 head: 0080000000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff head: 0000000000000000 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 22801572255 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1871 prep_new_page mm/page_alloc.c:1879 [inline] get_page_from_freelist+0x2591/0x2600 mm/page_alloc.c:3943 __alloc_frozen_pages_noprof+0x230/0x5c0 mm/page_alloc.c:5436 alloc_slab_page mm/slub.c:3347 [inline] allocate_slab+0x7d/0x620 mm/slub.c:3462 new_slab mm/slub.c:3513 [inline] refill_objects+0x2d8/0x350 mm/slub.c:7410 refill_sheaf mm/slub.c:2885 [inline] __pcs_replace_empty_main+0x339/0x690 mm/slub.c:4774 alloc_from_pcs mm/slub.c:4850 [inline] slab_alloc_node mm/slub.c:4984 [inline] __kmalloc_cache_noprof+0x46f/0x680 mm/slub.c:5559 _kmalloc_noprof include/linux/slab.h:991 [inline] _kzalloc_noprof include/linux/slab.h:1312 [inline] usb_hub_create_port_device+0x7d/0xc40 drivers/usb/core/port.c:759 hub_configure drivers/usb/core/hub.c:1739 [inline] hub_probe+0x26d6/0x3c20 drivers/usb/core/hub.c:2006 usb_probe_interface+0x788/0xe50 drivers/usb/core/driver.c:399 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x254/0xae0 drivers/base/dd.c:706 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868 driver_probe_device+0x4f/0x240 drivers/base/dd.c:898 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1026 bus_for_each_drv+0x25b/0x2f0 drivers/base/bus.c:500 __device_attach+0x2c7/0x450 drivers/base/dd.c:1098 page_owner free stack trace missing Memory state around the buggy address: ffff88802b714380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88802b714400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88802b714480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88802b714500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88802b714580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Tested on: commit: 50d05c7c Merge tag 'landlock-7.3-rc3' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17722c8e580000 kernel config: https://syzkaller.appspot.com/x/.config?x=e618aabdc2dca7e6 dashboard link: https://syzkaller.appspot.com/bug?extid=bca09f5d8b843bbf7571 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 patch: https://syzkaller.appspot.com/x/patch.diff?x=1578aef9580000