From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Bennett Date: Tue, 05 Jul 2016 02:50:54 +0000 Subject: Problem: BUG_ON hit in ppp_pernet() when re-connect after changing shared key on LAC Message-Id: <7fabf4defe2f468bbcc829247de956c0@svr-chch-ex1.atlnz.lc> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable To: "linux-ppp@vger.kernel.org" , "netdev@vger.kernel.org" Cc: "g.nault@alphalink.fr" Hi, I am producing the attached bug trace when testing PPP connections.=20 Specifically the steps I am doing are: 1. Configure PPP client and LAC with shared key and wait for client to=20 negotiate an IP address. 2. Change the shared key on the LAC. 3. Bring the PPP client interface down and up to make it reconnect. 4. Repeat down/up until bug occurs. Using printk I have confirmed that ppp_pernet() is called from=20 ppp_connect_channel() when the BUG occurs (i.e. pch->chan_net is NULL). This behavior appears to have been introduced in commit 1f461dc ("ppp:=20 take reference on channels netns"). Thanks, Matt ------- Kernel bug detected[#1]: CPU: 0 PID: 1796 Comm: pppd Tainted: P O 4.4.6-at1 #1 task: 800000004cf9a610 ti: 80000000009b8000 task.ti: 80000000009b8000 $ 0 : 0000000000000000 0000000000000001 0000000000000000 0000000000000001 $ 4 : 8000000005174560 8000000005174560 8000000005175b30 00000000048d0550 $ 8 : 0000000004830000 0000000000000000 0000000000005fd8 0000000004900000 $12 : ffffffff80000000 8000000004900000 0000000000000014 0000000000000000 $16 : 0000000000000001 80000000008ec480 0000000010069dc4 fffffffffffffff2 $20 : 8000000004840000 80000000008ec4f8 000000001008e708 0000000010010000 $24 : 0000000004900000 0000000004900000 $28 : 80000000009b8000 80000000009bbd00 800000004c777d80 800000000438ade8 Hi : 0000000000000000 Lo : 09cd1da35f400000 epc : 800000000438a5c8 ppp_ioctl+0x868/0x1098 ra : 800000000438ade8 ppp_ioctl+0x1088/0x1098 Status: 10009ce3 KX SX UX KERNEL EXL IE Cause : 00800034 (ExcCode 0d) PrId : 000d9602 (Cavium Octeon III) Modules linked in: jitterentropy_rng echainiv drbg linux_user_bde(PO)=20 linux_kernel_bde(PO) platform_driver(O) ipifwd(PO ) Process pppd (pid: 1796, threadinfo=80000000009b8000,=20 task=800000004cf9a610, tls=000000ffee40b700) Stack : 0000000000000001 800000004cf9aa00 800000000480f1f8 80000000048d4600 ffffffff80000000 8000000005188600 0000000010020000=20 8000000004086dc0 0000000010069dc4 800000004c777d80 800000004f90bba8=20 000000000000000b 0000000010069dc4 ffffffff8004743a 000000001008e708=20 0000000010010000 0000000010020000 800000000414e318 0000000000000001=20 800000004cf9a610 8000000005188600 8000000001440190 800000000480df00=20 80000000015126a0 80000000015126a0 80000000046792ac 80000000010ef080=20 0000000000000004 800000004c777d80 800000004c777d80 0000000010070000=20 800000004c777d80 000000000000000b 800000000414e930 0000000000000011=20 0000000010044438 000000000000000b ffffffffffffffff 000000001003eb80=20 000000001003ec10 ... Call Trace: [<800000000438a5c8>] ppp_ioctl+0x868/0x1098 [<800000000414e318>] do_vfs_ioctl+0x98/0x620 [<800000000414e930>] SyS_ioctl+0x90/0xd0 [<8000000004035e80>] syscall_common+0x44/0x68 Code: de2200a0 10400202 0000182d <00030336> 3c038000 3c080481=20 dc421420 64630000 0003183c ---[ end trace 72203e44575f38a6 ]---