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09 Sep 2026 06:19:02 -0700 In-Reply-To: <20260909130533.9011-1-syedtayyabfarooq08@gmail.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6aa15cc6.f2639fcc.29487d.0007.GAE@google.com> Subject: Re: [syzbot] [serial?] KASAN: slab-use-after-free Write in tty_init_dev From: syzbot To: linux-kernel@vger.kernel.org, syedtayyabfarooq08@gmail.com, 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 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:165 [inline] BUG: KASAN: slab-use-after-free in _raw_spin_lock_irq+0x36/0x50 kernel/locking/spinlock.c:189 Read of size 1 at addr ffff8880364433a0 by task syz-executor276/6040 CPU: 2 UID: 0 PID: 6040 Comm: syz-executor276 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x13d/0x4b0 mm/kasan/report.c:482 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595 __kasan_check_byte+0x36/0x50 mm/kasan/common.c:574 kasan_check_byte include/linux/kasan.h:402 [inline] lock_acquire kernel/locking/lockdep.c:5916 [inline] lock_acquire+0x132/0x380 kernel/locking/lockdep.c:5899 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:165 [inline] _raw_spin_lock_irq+0x36/0x50 kernel/locking/spinlock.c:189 spin_lock_irq include/linux/spinlock.h:377 [inline] gs_close+0xc6/0xcd0 drivers/usb/gadget/function/u_serial.c:736 tty_release+0x40e/0x1300 drivers/tty/tty_io.c:1718 tty_open+0x31d/0xe20 drivers/tty/tty_io.c:2119 chrdev_open+0x234/0x6a0 fs/char_dev.c:411 do_dentry_open+0x6ab/0x14d0 fs/open.c:996 vfs_open+0x82/0x3f0 fs/open.c:1101 do_open fs/namei.c:4837 [inline] path_openat+0x19fa/0x2440 fs/namei.c:5000 do_file_open+0x20e/0x430 fs/namei.c:5029 do_sys_openat2+0x10f/0x1e0 fs/open.c:1417 do_sys_open fs/open.c:1423 [inline] __do_sys_openat fs/open.c:1439 [inline] __se_sys_openat fs/open.c:1434 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1434 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb0988eba1e Code: 08 0f 85 f5 e2 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:00007fb098896158 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fb0988966c0 RCX: 00007fb0988eba1e RDX: 0000000000000002 RSI: 00007fb098937028 RDI: ffffffffffffff9c RBP: 0000000000000021 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffd0 R13: 0000000000000000 R14: 00007ffc902179f0 R15: 00007ffc90217ad8 Allocated by task 6038: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x2f8/0x6d0 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:1269 [inline] gserial_alloc_line_no_console+0xac/0x740 drivers/usb/gadget/function/u_serial.c:1349 gserial_alloc_line+0x16/0xa0 drivers/usb/gadget/function/u_serial.c:1383 acm_alloc_instance+0xd9/0x160 drivers/usb/gadget/function/f_acm.c:891 try_get_usb_function_instance+0x136/0x1f0 drivers/usb/gadget/functions.c:28 usb_get_function_instance+0x16/0x70 drivers/usb/gadget/functions.c:44 function_make+0x18c/0x3f0 drivers/usb/gadget/configfs.c:626 configfs_mkdir+0x525/0xd40 fs/configfs/dir.c:1369 vfs_mkdir+0x364/0x850 fs/namei.c:5410 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5443 __do_sys_mkdir fs/namei.c:5470 [inline] __se_sys_mkdir fs/namei.c:5467 [inline] __x64_sys_mkdir+0x6b/0x90 fs/namei.c:5467 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 6038: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/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+0x22b/0x6d0 mm/slub.c:6792 tty_port_destructor drivers/tty/tty_port.c:294 [inline] kref_put include/linux/kref.h:65 [inline] tty_port_put drivers/tty/tty_port.c:309 [inline] tty_port_put+0x18d/0x1e0 drivers/tty/tty_port.c:306 gserial_free_port+0x13e/0x2f0 drivers/usb/gadget/function/u_serial.c:1313 gserial_free_line+0xf8/0x1e0 drivers/usb/gadget/function/u_serial.c:1330 acm_free_instance+0x3b/0x60 drivers/usb/gadget/function/f_acm.c:875 usb_put_function_instance+0x97/0xc0 drivers/usb/gadget/functions.c:77 config_item_cleanup+0x146/0x240 fs/configfs/item.c:128 config_item_release fs/configfs/item.c:137 [inline] kref_put include/linux/kref.h:65 [inline] config_item_put fs/configfs/item.c:149 [inline] config_item_put+0x93/0xb0 fs/configfs/item.c:146 configfs_rmdir+0x5e3/0x950 fs/configfs/dir.c:1580 vfs_rmdir fs/namei.c:5515 [inline] vfs_rmdir+0x328/0x8a0 fs/namei.c:5488 filename_rmdir+0x31a/0x5c0 fs/namei.c:5572 __do_sys_rmdir fs/namei.c:5595 [inline] __se_sys_rmdir fs/namei.c:5592 [inline] __x64_sys_rmdir+0x46/0x70 fs/namei.c:5592 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff888036443000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 928 bytes inside of freed 2048-byte region [ffff888036443000, ffff888036443800) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x36440 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 ffff88801c042f00 dead000000000100 dead000000000122 raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801c042f00 dead000000000100 dead000000000122 head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000 head: 00fff00000000003 fffffffffffffe01 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6038, tgid 6038 (syz-executor276), ts 77096280293 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1871 prep_new_page mm/page_alloc.c:1879 [inline] get_page_from_freelist+0x110d/0x35d0 mm/page_alloc.c:3943 __alloc_frozen_pages_noprof+0x2eb/0x3300 mm/page_alloc.c:5436 alloc_slab_page mm/slub.c:3347 [inline] allocate_slab mm/slub.c:3462 [inline] new_slab+0xa9/0x6e0 mm/slub.c:3513 refill_objects+0xe3/0x410 mm/slub.c:7410 refill_sheaf mm/slub.c:2885 [inline] __pcs_replace_empty_main+0x35e/0x650 mm/slub.c:4774 alloc_from_pcs mm/slub.c:4850 [inline] slab_alloc_node mm/slub.c:4984 [inline] __kmalloc_cache_noprof+0x4f4/0x6d0 mm/slub.c:5559 _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:1269 [inline] gserial_alloc_line_no_console+0xac/0x740 drivers/usb/gadget/function/u_serial.c:1349 gserial_alloc_line+0x16/0xa0 drivers/usb/gadget/function/u_serial.c:1383 acm_alloc_instance+0xd9/0x160 drivers/usb/gadget/function/f_acm.c:891 try_get_usb_function_instance+0x136/0x1f0 drivers/usb/gadget/functions.c:28 usb_get_function_instance+0x16/0x70 drivers/usb/gadget/functions.c:44 function_make+0x18c/0x3f0 drivers/usb/gadget/configfs.c:626 configfs_mkdir+0x525/0xd40 fs/configfs/dir.c:1369 vfs_mkdir+0x364/0x850 fs/namei.c:5410 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5443 page last free pid 1169 tgid 1169 ts 76886153795 stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] __free_pages_prepare mm/page_alloc.c:1418 [inline] __free_frozen_pages+0x79f/0x10f0 mm/page_alloc.c:2962 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4683 [inline] slab_alloc_node mm/slub.c:4996 [inline] kmem_cache_alloc_noprof+0x269/0x6a0 mm/slub.c:5010 copy_signal kernel/fork.c:1746 [inline] copy_process+0x3075/0x8370 kernel/fork.c:2304 kernel_clone+0x176/0x9d0 kernel/fork.c:2766 user_mode_thread+0xd1/0x120 kernel/fork.c:2843 call_usermodehelper_exec_sync kernel/umh.c:130 [inline] call_usermodehelper_exec_work+0x6b/0x180 kernel/umh.c:161 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396 process_scheduled_works kernel/workqueue.c:3479 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Memory state around the buggy address: ffff888036443280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888036443300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888036443380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888036443400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888036443480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Tested on: commit: 893e1178 Merge tag 'x86_urgent_for_7.3-rc3' of git://g.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=167e2ef9580000 kernel config: https://syzkaller.appspot.com/x/.config?x=8c5c3949d762a91f dashboard link: https://syzkaller.appspot.com/bug?extid=fe63e4d633540f230624 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 patch: https://syzkaller.appspot.com/x/patch.diff?x=1006d749580000