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[42.60.144.185]) by smtp.gmail.com with ESMTPSA id s3sm3506467pfk.61.2021.07.29.05.05.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 29 Jul 2021 05:05:10 -0700 (PDT) Subject: Re: memory leak in h4_recv_buf To: Marcel Holtmann Cc: syzkaller-bugs , Johan Hedberg , linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org References: <0000000000006b1779058c0cbdda@google.com> From: Phi Nguyen Message-ID: <82554b3b-1b0e-6202-bb97-d969997c10b2@gmail.com> Date: Thu, 29 Jul 2021 20:05:07 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/29/2021 7:44 PM, Marcel Holtmann wrote: > Hi Phi, > >>> Hello, >>> syzbot found the following crash on: >>> HEAD commit: abf02e29 Merge tag 'pm-5.2-rc6' of >>> git://git.kernel.org/pu .. >>> git tree: upstream >>> console output: >>> https://syzkaller.appspot.com/x/log.txt?x=1054e6b2a00000 >>> >>> kernel config: >>> https://syzkaller.appspot.com/x/.config?x=56f1da14935c3cce >>> >>> dashboard link: >>> https://syzkaller.appspot.com/bug?extid=97388eb9d31b997fe1d0 >>> >>> compiler: gcc (GCC) 9.0.0 20181231 (experimental) >>> syz repro: >>> https://syzkaller.appspot.com/x/repro.syz?x=1073d8aaa00000 >>> >>> C reproducer: >>> https://syzkaller.appspot.com/x/repro.c?x=17b36fbea00000 >>> >>> IMPORTANT: if you fix the bug, please add the following tag to the >>> commit: >>> Reported-by: syzbot+97388e...@syzkaller.appspotmail.com >>> program >>> BUG: memory leak >>> unreferenced object 0xffff88810991fa00 (size 224): >>> comm "syz-executor739", pid 7080, jiffies 4294949854 (age 18.640s) >>> hex dump (first 32 bytes): >>> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >>> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >>> backtrace: >>> [<00000000da42c09f>] kmemleak_alloc_recursive >>> include/linux/kmemleak.h:43 [inline] >>> [<00000000da42c09f>] slab_post_alloc_hook mm/slab.h:439 [inline] >>> [<00000000da42c09f>] slab_alloc_node mm/slab.c:3269 [inline] >>> [<00000000da42c09f>] kmem_cache_alloc_node+0x153/0x2a0 mm/slab.c:3579 >>> [<00000000f6fbcf84>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:194 >>> [<00000000ea93fc4c>] alloc_skb include/linux/skbuff.h:1054 [inline] >>> [<00000000ea93fc4c>] bt_skb_alloc include/net/bluetooth/bluetooth.h:339 >>> [inline] >>> [<00000000ea93fc4c>] h4_recv_buf+0x26d/0x450 >>> drivers/bluetooth/hci_h4.c:182 >>> [<00000000e0312475>] h4_recv+0x51/0xb0 drivers/bluetooth/hci_h4.c:116 >>> [<00000000ebf11fab>] hci_uart_tty_receive+0xba/0x200 >>> drivers/bluetooth/hci_ldisc.c:592 >>> [<0000000095e1216e>] tiocsti drivers/tty/tty_io.c:2195 [inline] >>> [<0000000095e1216e>] tty_ioctl+0x81c/0xa30 drivers/tty/tty_io.c:2571 >>> [<000000009fa523f0>] vfs_ioctl fs/ioctl.c:46 [inline] >>> [<000000009fa523f0>] file_ioctl fs/ioctl.c:509 [inline] >>> [<000000009fa523f0>] do_vfs_ioctl+0x62a/0x810 fs/ioctl.c:696 >>> [<000000000cebb5d9>] ksys_ioctl+0x86/0xb0 fs/ioctl.c:713 >>> [<000000001630008a>] __do_sys_ioctl fs/ioctl.c:720 [inline] >>> [<000000001630008a>] __se_sys_ioctl fs/ioctl.c:718 [inline] >>> [<000000001630008a>] __x64_sys_ioctl+0x1e/0x30 fs/ioctl.c:718 >>> [<00000000c62091e3>] do_syscall_64+0x76/0x1a0 >>> arch/x86/entry/common.c:301 >>> [<000000005c213625>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 >>> BUG: memory leak >>> unreferenced object 0xffff8881204f4400 (size 1024): >>> comm "syz-executor739", pid 7080, jiffies 4294949854 (age 18.640s) >>> hex dump (first 32 bytes): >>> 6c 69 62 75 64 65 76 00 fe ed ca fe 28 00 00 00 libudev.....(... >>> 28 00 00 00 a0 00 00 00 52 ca da 77 00 00 00 00 (.......R..w.... >>> backtrace: >>> [<0000000034504843>] kmemleak_alloc_recursive >>> include/linux/kmemleak.h:43 [inline] >>> [<0000000034504843>] slab_post_alloc_hook mm/slab.h:439 [inline] >>> [<0000000034504843>] slab_alloc_node mm/slab.c:3269 [inline] >>> [<0000000034504843>] kmem_cache_alloc_node_trace+0x15b/0x2a0 >>> mm/slab.c:3597 >>> [<0000000056d30eb5>] __do_kmalloc_node mm/slab.c:3619 [inline] >>> [<0000000056d30eb5>] __kmalloc_node_track_caller+0x38/0x50 >>> mm/slab.c:3634 >>> [<00000000df40176c>] __kmalloc_reserve.isra.0+0x40/0xb0 >>> net/core/skbuff.c:138 >>> [<0000000035340e64>] __alloc_skb+0xa0/0x210 net/core/skbuff.c:206 >>> [<00000000ea93fc4c>] alloc_skb include/linux/skbuff.h:1054 [inline] >>> [<00000000ea93fc4c>] bt_skb_alloc include/net/bluetooth/bluetooth.h:339 >>> [inline] >>> [<00000000ea93fc4c>] h4_recv_buf+0x26d/0x450 >>> drivers/bluetooth/hci_h4.c:182 >>> [<00000000e0312475>] h4_recv+0x51/0xb0 drivers/bluetooth/hci_h4.c:116 >>> [<00000000ebf11fab>] hci_uart_tty_receive+0xba/0x200 >>> drivers/bluetooth/hci_ldisc.c:592 >>> [<0000000095e1216e>] tiocsti drivers/tty/tty_io.c:2195 [inline] >>> [<0000000095e1216e>] tty_ioctl+0x81c/0xa30 drivers/tty/tty_io.c:2571 >>> [<000000009fa523f0>] vfs_ioctl fs/ioctl.c:46 [inline] >>> [<000000009fa523f0>] file_ioctl fs/ioctl.c:509 [inline] >>> [<000000009fa523f0>] do_vfs_ioctl+0x62a/0x810 fs/ioctl.c:696 >>> [<000000000cebb5d9>] ksys_ioctl+0x86/0xb0 fs/ioctl.c:713 >>> [<000000001630008a>] __do_sys_ioctl fs/ioctl.c:720 [inline] >>> [<000000001630008a>] __se_sys_ioctl fs/ioctl.c:718 [inline] >>> [<000000001630008a>] __x64_sys_ioctl+0x1e/0x30 fs/ioctl.c:718 >>> [<00000000c62091e3>] do_syscall_64+0x76/0x1a0 >>> arch/x86/entry/common.c:301 >>> [<000000005c213625>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 >>> --- >>> This bug is generated by a bot. It may contain errors. >>> See https://goo.gl/tpsmEJ for more >>> information about syzbot. >>> syzbot engineers can be reached at syzk...@googlegroups.com. >>> syzbot will keep track of this bug report. See: >>> https://goo.gl/tpsmEJ#status for how >>> to communicate with syzbot. >>> syzbot can test patches for this bug, for details see: >>> https://goo.gl/tpsmEJ#testing-patches >>> >>> -- >>> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. >>> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com . >>> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/d71a274f-fdeb-4da1-898e-06f6944e04dan%40googlegroups.com . >> >> The reason of this memory leak is tty_ldisc_receive_buf() and tiocsti() >> can access the h4->rx_skb concurrently by calling >> hci_uart_tty_receive(), so the rx_skb be overwritten without >> deallocating. There used to be an spin_lock in hci_uart_tty_receive(), >> but it was removed by commit 7649ffaff1cfe(Bluetooth: Remove useless >> rx_lock spinlock). > > I don’t have that commit in my Linus’ tree. Where is it? > >> The commit message claims that hci_uart_tty_receive() was only called by >> flush_to_ldisc(), but it seems incorrect. > > That seems to be a larger problem in the TTY layer if its contract with its users have changed. > > Regards > > Marcel > Hi Marcel, It was my typo, the git hash should be 7649faff1cfe4. Regards, Phi.