From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa1-f69.google.com (mail-oa1-f69.google.com [209.85.160.69]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 296F43F6618 for ; Wed, 26 Aug 2026 16:49:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.69 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787762995; cv=none; b=kRfE5/qKmTI8DLCmvaytY7joA1cglms/VSZIIXKX5CLR1t3XeQSOM1IqxaZQb55QzebxZh9Arc44PfqMangC32kfue2pt+WUPVc9ZlDgimGcuK4u0gp9zGRUnwu1JOO/eU1afpLQZBfZaF2LtuUPdUS+gNH+WJzuJd4hUYyaAYk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787762995; c=relaxed/simple; bh=phsbyYf7Boh6K8o1ijxZ80eQZFGXbuMPeGJ9bwUfdkY=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; 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2002:a05:6820:4def:b0:6b1:5c1b:582f with SMTP id 006d021491bc7-6b1a0388a21mr7741330eaf.5.1787762976565; Wed, 26 Aug 2026 09:49:36 -0700 (PDT) Date: Wed, 26 Aug 2026 09:49:36 -0700 In-Reply-To: <6a68bbd5.073198cf.94f0f.004a.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a8f1920.1d9ded08.62e62.00b7.GAE@google.com> Subject: Re: [syzbot] [usb?] KASAN: slab-use-after-free Read in stub_rx_loop From: syzbot To: gregkh@linuxfoundation.org, i@zenithal.me, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, shuah@kernel.org, syzkaller-bugs@googlegroups.com, valentina.manea.m@gmail.com Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 818bebeb63dd drm/xe: Don't hand out the flat CCS storage a.. git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git console output: https://syzkaller.appspot.com/x/log.txt?x=151ce979580000 kernel config: https://syzkaller.appspot.com/x/.config?x=ccca94d2c01b9e78 dashboard link: https://syzkaller.appspot.com/bug?extid=06fa667a0931a3430026 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13a28d49580000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+06fa667a0931a3430026@syzkaller.appspotmail.com ================================================================== BUG: KASAN: slab-use-after-free in stub_recv_cmd_submit drivers/usb/usbip/stub_rx.c:609 [inline] BUG: KASAN: slab-use-after-free in stub_rx_pdu drivers/usb/usbip/stub_rx.c:688 [inline] BUG: KASAN: slab-use-after-free in stub_rx_loop+0x2d3b/0x31c0 drivers/usb/usbip/stub_rx.c:707 Read of size 4 at addr ffff888034999db0 by task stub_rx/6028 CPU: 0 UID: 0 PID: 6028 Comm: stub_rx 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 stub_recv_cmd_submit drivers/usb/usbip/stub_rx.c:609 [inline] stub_rx_pdu drivers/usb/usbip/stub_rx.c:688 [inline] stub_rx_loop+0x2d3b/0x31c0 drivers/usb/usbip/stub_rx.c:707 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 Allocated by task 6028: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4586 [inline] slab_alloc_node mm/slub.c:4919 [inline] kmem_cache_alloc_noprof+0x26b/0x6a0 mm/slub.c:4933 stub_priv_alloc drivers/usb/usbip/stub_rx.c:314 [inline] stub_recv_cmd_submit drivers/usb/usbip/stub_rx.c:490 [inline] stub_rx_pdu drivers/usb/usbip/stub_rx.c:688 [inline] stub_rx_loop+0x638/0x31c0 drivers/usb/usbip/stub_rx.c:707 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 Freed by task 6029: 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:2678 [inline] slab_free mm/slub.c:6372 [inline] kmem_cache_free+0x127/0x6b0 mm/slub.c:6499 stub_free_priv_and_urb+0x427/0x570 drivers/usb/usbip/stub_main.c:321 stub_send_ret_submit+0xecf/0x1810 drivers/usb/usbip/stub_tx.c:333 stub_tx_loop+0xe2/0x3e0 drivers/usb/usbip/stub_tx.c:437 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 The buggy address belongs to the object at ffff888034999d80 which belongs to the cache stub_priv of size 64 The buggy address is located 48 bytes inside of freed 64-byte region [ffff888034999d80, ffff888034999dc0) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888034999e00 pfn:0x34999 flags: 0xfff00000000200(workingset|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000200 ffff8881016c7540 ffff88802aafa948 ffff88802aafa948 raw: ffff888034999e00 000000080020001c 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 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6028, tgid 6028 (stub_rx), ts 78215496489 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/0x35b0 mm/page_alloc.c:3943 __alloc_frozen_pages_noprof+0x2eb/0x3300 mm/page_alloc.c:5436 alloc_slab_page mm/slub.c:3267 [inline] allocate_slab mm/slub.c:3382 [inline] new_slab+0xa5/0x640 mm/slub.c:3428 refill_objects+0xe3/0x410 mm/slub.c:7305 refill_sheaf mm/slub.c:2805 [inline] __pcs_replace_empty_main+0x372/0x680 mm/slub.c:4677 alloc_from_pcs mm/slub.c:4775 [inline] slab_alloc_node mm/slub.c:4907 [inline] kmem_cache_alloc_noprof+0x46e/0x6a0 mm/slub.c:4933 stub_priv_alloc drivers/usb/usbip/stub_rx.c:314 [inline] stub_recv_cmd_submit drivers/usb/usbip/stub_rx.c:490 [inline] stub_rx_pdu drivers/usb/usbip/stub_rx.c:688 [inline] stub_rx_loop+0x638/0x31c0 drivers/usb/usbip/stub_rx.c:707 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 page last free pid 15 tgid 15 ts 77527058318 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 __pagetable_free include/linux/mm.h:3745 [inline] pagetable_free include/linux/mm.h:3769 [inline] pagetable_dtor_free include/linux/mm.h:3868 [inline] __tlb_remove_table include/asm-generic/tlb.h:221 [inline] __tlb_remove_table_free mm/mmu_gather.c:228 [inline] tlb_remove_table_rcu+0x2cf/0x380 mm/mmu_gather.c:291 rcu_do_batch kernel/rcu/tree.c:2645 [inline] rcu_core+0x5a2/0x10e0 kernel/rcu/tree.c:2897 handle_softirqs+0x1e6/0x9d0 kernel/softirq.c:645 __do_softirq kernel/softirq.c:679 [inline] invoke_softirq kernel/softirq.c:519 [inline] __irq_exit_rcu+0x194/0x210 kernel/softirq.c:767 irq_exit_rcu+0x9/0x30 kernel/softirq.c:784 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 Memory state around the buggy address: ffff888034999c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888034999d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888034999d80: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ffff888034999e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888034999e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.