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[143.248.133.220]) by smtp.gmail.com with ESMTPSA id c13-20020a170902c1cd00b0019f2328bef8sm15453785plc.34.2023.03.25.01.18.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 25 Mar 2023 01:18:38 -0700 (PDT) Date: Sat, 25 Mar 2023 17:18:34 +0900 From: "Dae R. Jeong" To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, jirislaby@kernel.org, duoming@zju.edu.cn, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: KASAN: use-after-free Read in slip_ioctl Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hello, We observed a use-after-free in slip_ioctl as attached at the end. Although I'm not sure that our analysis is correct, it seems that the concurrent execution of slip_ioctl() and slip_close() causes the issue as follows. CPU1 CPU2 slip_ioctl slip_close (via slip_hangup) ----- ----- // Read a non-null value sl = tty->disc_data; // Nullify tty->disc_data and then // unregister sl->dev rcu_assign_pointer(tty->disc_data, NULL); unregister_netdev(sl->dev); // sl is freed in unregister_netdev() if (!sl || sl->magic != SLIP_MAGIC) return -EINVAL; I suspect that the two functions can be executed concurrently as I don't see a locking mechanism to prevent this in tty_ioctl(), and that sl is freed in unregister_netdev() as explained in the callstack. But still we need to look into this further. Best regards, Dae R. Jeong ================================================================== BUG: KASAN: use-after-free in slip_ioctl+0x6db/0x7d0 drivers/net/slip/slip.c:1083 Read of size 4 at addr ffff88804b856c80 by task syz-executor.0/9106 CPU: 2 PID: 9106 Comm: syz-executor.0 Not tainted 6.0.0-rc7-00166-gf09dbf1cf0d5 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1cf/0x2b7 lib/dump_stack.c:106 print_address_description+0x21/0x470 mm/kasan/report.c:317 print_report+0x108/0x1f0 mm/kasan/report.c:433 kasan_report+0xe5/0x110 mm/kasan/report.c:495 slip_ioctl+0x6db/0x7d0 drivers/net/slip/slip.c:1083 tty_ioctl+0x11e9/0x1a20 drivers/tty/tty_io.c:2787 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0x110/0x180 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4e/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x478d29 Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fbbbdfb8be8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000781408 RCX: 0000000000478d29 RDX: 0000000020000040 RSI: 00000000402c542c RDI: 0000000000000003 RBP: 00000000f477909a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000781580 r13: 0000000000781414 R14: 0000000000781408 R15: 00007ffcfdc4f040 Allocated by task 9103: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:437 [inline] ____kasan_kmalloc+0xcd/0x100 mm/kasan/common.c:516 kasan_kmalloc include/linux/kasan.h:234 [inline] __kmalloc_node+0x366/0x550 mm/slub.c:4477 kmalloc_node include/linux/slab.h:623 [inline] kvmalloc_node+0x6e/0x170 mm/util.c:613 kvmalloc include/linux/slab.h:750 [inline] kvzalloc include/linux/slab.h:758 [inline] alloc_netdev_mqs+0x86/0x1240 net/core/dev.c:10603 sl_alloc drivers/net/slip/slip.c:756 [inline] slip_open+0x489/0x1240 drivers/net/slip/slip.c:817 tty_ldisc_open+0xb4/0x120 drivers/tty/tty_ldisc.c:433 tty_set_ldisc+0x366/0x860 drivers/tty/tty_ldisc.c:558 tiocsetd drivers/tty/tty_io.c:2433 [inline] tty_ioctl+0x168f/0x1a20 drivers/tty/tty_io.c:2714 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0x110/0x180 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4e/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 9105: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x3d/0x60 mm/kasan/common.c:45 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x134/0x1c0 mm/kasan/common.c:367 kasan_slab_free include/linux/kasan.h:200 [inline] slab_free_hook mm/slub.c:1759 [inline] slab_free_freelist_hook+0x278/0x370 mm/slub.c:1785 slab_free mm/slub.c:3539 [inline] kfree+0x108/0x460 mm/slub.c:4567 device_release+0x189/0x220 kobject_cleanup+0x24f/0x360 lib/kobject.c:673 netdev_run_todo+0x14ac/0x15a0 net/core/dev.c:10385 unregister_netdev+0x1e9/0x270 net/core/dev.c:10922 tty_ldisc_hangup+0x224/0x750 drivers/tty/tty_ldisc.c:700 __tty_hangup+0x5b4/0x870 drivers/tty/tty_io.c:637 tty_vhangup drivers/tty/tty_io.c:707 [inline] tty_ioctl+0xa7f/0x1a20 drivers/tty/tty_io.c:2718 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0x110/0x180 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4e/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0xcd The buggy address belongs to the object at ffff88804b856000 which belongs to the cache kmalloc-cg-4k of size 4096 The buggy address is located 3200 bytes inside of 4096-byte region [ffff88804b856000, ffff88804b857000) The buggy address belongs to the physical page: page:ffffea00012e1400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4b850 head:ffffea00012e1400 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 ffffea000421c600 dead000000000003 ffff88801344c140 raw: 0000000000000000 0000000080040004 00000001ffffffff 0000000000000000 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 3028, tgid 3028 (systemd-udevd), ts 3568645047764, free_ts 3567951761241 prep_new_page mm/page_alloc.c:2532 [inline] get_page_from_freelist+0x800/0xc10 mm/page_alloc.c:4283 __alloc_pages+0x2f0/0x650 mm/page_alloc.c:5549 alloc_slab_page mm/slub.c:1829 [inline] allocate_slab+0x1eb/0xc00 mm/slub.c:1974 new_slab mm/slub.c:2034 [inline] ___slab_alloc+0x581/0xff0 mm/slub.c:3036 __slab_alloc mm/slub.c:3123 [inline] slab_alloc_node mm/slub.c:3214 [inline] __kmalloc_node+0x3db/0x550 mm/slub.c:4473 kmalloc_node include/linux/slab.h:623 [inline] kvmalloc_node+0x6e/0x170 mm/util.c:613 kvmalloc include/linux/slab.h:750 [inline] seq_buf_alloc fs/seq_file.c:38 [inline] seq_read_iter+0x269/0x10f0 fs/seq_file.c:210 call_read_iter include/linux/fs.h:2181 [inline] new_sync_read fs/read_write.c:389 [inline] vfs_read+0x838/0xd30 fs/read_write.c:470 ksys_read+0x182/0x2c0 fs/read_write.c:607 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4e/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0xcd page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1449 [inline] free_pcp_prepare+0x76d/0x890 mm/page_alloc.c:1499 free_unref_page_prepare mm/page_alloc.c:3380 [inline] free_unref_page+0x8a/0x880 mm/page_alloc.c:3476 __skb_frag_unref include/linux/skbuff.h:3380 [inline] skb_release_data+0x3f0/0x910 net/core/skbuff.c:685 skb_release_all net/core/skbuff.c:756 [inline] __kfree_skb+0x60/0x210 net/core/skbuff.c:770 e1000_unmap_and_free_tx_resource drivers/net/ethernet/intel/e1000/e1000_main.c:1970 [inline] e1000_clean_tx_irq drivers/net/ethernet/intel/e1000/e1000_main.c:3860 [inline] e1000_clean+0x5ba/0x4400 drivers/net/ethernet/intel/e1000/e1000_main.c:3801 __napi_poll+0xe7/0x6b0 net/core/dev.c:6511 napi_poll net/core/dev.c:6578 [inline] net_rx_action+0x7a5/0x1210 net/core/dev.c:6689 __do_softirq+0x372/0x783 kernel/softirq.c:571 Memory state around the buggy address: ffff88804b856b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88804b856c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88804b856c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88804b856d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88804b856d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================