From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751161AbeAVNqU (ORCPT ); Mon, 22 Jan 2018 08:46:20 -0500 Received: from mail-oi0-f68.google.com ([209.85.218.68]:42490 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751070AbeAVNqS (ORCPT ); Mon, 22 Jan 2018 08:46:18 -0500 X-Google-Smtp-Source: AH8x2247VNn79FK7QDumje0aRIGwa3ynCqk+CyOejwghc3QTfZcrTYcfzzqZiKagFa1waT9y7Q60Sw== Reply-To: minyard@acm.org Subject: Re: [PATCH] ipmi: use dynamic memory for DMI driver override To: John Garry , openipmi-developer@lists.sourceforge.net Cc: linuxarm@huawei.com, linux-kernel@vger.kernel.org References: <1516207017-158659-1-git-send-email-john.garry@huawei.com> <691ee7e1-89fd-2f9f-9b69-1c040ea77c12@huawei.com> From: Corey Minyard Message-ID: <704da5f1-b234-2385-4169-dcbe2bbaaa91@acm.org> Date: Mon, 22 Jan 2018 07:46:15 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <691ee7e1-89fd-2f9f-9b69-1c040ea77c12@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/17/2018 11:06 AM, John Garry wrote: > On 17/01/2018 16:49, Corey Minyard wrote: >> On 01/17/2018 10:36 AM, John Garry wrote: >>> Currently a crash can be seen if we reach the "err" >>> label in dmi_add_platform_ipmi(), calling >>> platform_device_put(), like here: >>> [    7.270584]  (null): ipmi:dmi: Unable to add resources: -16 >>> [    7.330229] ------------[ cut here ]------------ >>> [    7.334889] kernel BUG at mm/slub.c:3894! >>> [    7.338936] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP >>> [    7.344475] Modules linked in: >>> [    7.347556] CPU: 1 PID: 1 Comm: swapper/0 Not tainted >>> 4.15.0-rc2-00004-gbe9cb7b-dirty #114 >>> [    7.355907] Hardware name: Huawei Taishan 2280 /D05, BIOS Hisilicon >>> D05 IT17 Nemo 2.0 RC0 11/29/2017 >>> [    7.365137] task: 00000000c211f6d3 task.stack: 00000000f276e9af >>> [    7.371116] pstate: 60000005 (nZCv daif -PAN -UAO) >>> [    7.375957] pc : kfree+0x194/0x1b4 >>> [    7.379389] lr : platform_device_release+0xcc/0xd8 >>> [    7.384225] sp : ffff0000092dba90 >>> [    7.387567] x29: ffff0000092dba90 x28: ffff000008a83000 >>> [    7.392933] x27: ffff0000092dbc10 x26: 00000000000000e6 >>> [    7.398297] x25: 0000000000000003 x24: ffff0000085b51e8 >>> [    7.403662] x23: 0000000000000100 x22: ffff7e0000234cc0 >>> [    7.409027] x21: ffff000008af3660 x20: ffff8017d21acc10 >>> [    7.414392] x19: ffff8017d21acc00 x18: 0000000000000002 >>> [    7.419757] x17: 0000000000000001 x16: 0000000000000008 >>> [    7.425121] x15: 0000000000000001 x14: 6666666678303d65 >>> [    7.430486] x13: 6469727265766f5f x12: 7265766972642e76 >>> [    7.435850] x11: 6564703e2d617020 x10: 6530326435373638 >>> [    7.441215] x9 : 3030303030303030 x8 : 3d76656420657361 >>> [    7.446580] x7 : ffff000008f59df8 x6 : ffff8017fbe0ea50 >>> [    7.451945] x5 : 0000000000000000 x4 : 0000000000000000 >>> [    7.457309] x3 : ffffffffffffffff x2 : 0000000000000000 >>> [    7.462674] x1 : 0fffc00000000800 x0 : ffff7e0000234ce0 >>> [    7.468039] Process swapper/0 (pid: 1, stack limit = >>> 0x00000000f276e9af) >>> [    7.474809] Call trace: >>> [    7.477272]  kfree+0x194/0x1b4 >>> [    7.480351]  platform_device_release+0xcc/0xd8 >>> [    7.484837]  device_release+0x34/0x90 >>> [    7.488531]  kobject_put+0x70/0xcc >>> [    7.491961]  put_device+0x14/0x1c >>> [    7.495304]  platform_device_put+0x14/0x1c >>> [    7.499439]  dmi_add_platform_ipmi+0x348/0x3ac >>> [    7.503923]  scan_for_dmi_ipmi+0xfc/0x10c >>> [    7.507970]  do_one_initcall+0x38/0x124 >>> [    7.511840]  kernel_init_freeable+0x188/0x228 >>> [    7.516238]  kernel_init+0x10/0x100 >>> [    7.519756]  ret_from_fork+0x10/0x18 >>> [    7.523362] Code: f94002c0 37780080 f94012c0 37000040 (d4210000) >>> [    7.529552] ---[ end trace 11750e4787deef9e ]--- >>> [    7.534228] Kernel panic - not syncing: Attempted to kill init! >>> exitcode=0x0000000b >>> [    7.534228] >>> >>> This is because when the device is released in >>> platform_device_release(), we try to free >>> pdev.driver_override. This is a const string, hence >>> the crash. >>> Fix by using dynamic memory for pdev->driver_override. >>> >>> Signed-off-by: John Garry >> >> Oops, sorry about that.  Yes, queued for the next release and 4.14.x. >> >> -corey >> >>> >>> diff --git a/drivers/char/ipmi/ipmi_dmi.c >>> b/drivers/char/ipmi/ipmi_dmi.c >>> index ab78b3b..c5112b1 100644 >>> --- a/drivers/char/ipmi/ipmi_dmi.c >>> +++ b/drivers/char/ipmi/ipmi_dmi.c >>> @@ -106,7 +106,10 @@ static void __init dmi_add_platform_ipmi(unsigned >>> long base_addr, >>>           pr_err("ipmi:dmi: Error allocation IPMI platform device\n"); >>>           return; >>>       } >>> -    pdev->driver_override = override; >>> +    pdev->driver_override = kasprintf(GFP_KERNEL, "%s", >>> +                      override); > > It would be simpler to use managed variant (to avoid the kfree()), but > I don't think it's possible until the device probes. > Actually, I don't think you should do the kfree() in ipmi_si_intf.c.  It's done in platform_device_release(), and will cause a double free if done in the IPMI code, unless you set it to NULL.  I'm going to add a patch to remove that hunk. -corey > John > >>> +    if (!pdev->driver_override) >>> +        goto err; >>>         if (type == IPMI_DMI_TYPE_SSIF) { >>>           set_prop_entry(p[pidx++], "i2c-addr", u16, base_addr); >>> diff --git a/drivers/char/ipmi/ipmi_si_intf.c >>> b/drivers/char/ipmi/ipmi_si_intf.c >>> index 779869e..2a19aa8 100644 >>> --- a/drivers/char/ipmi/ipmi_si_intf.c >>> +++ b/drivers/char/ipmi/ipmi_si_intf.c >>> @@ -2426,6 +2426,7 @@ int ipmi_si_remove_by_dev(struct device *dev) >>>   { >>>       struct smi_info *e; >>>       int rv = -ENOENT; >>> +    struct platform_device *pdev = to_platform_device(dev); >>>         mutex_lock(&smi_infos_lock); >>>       list_for_each_entry(e, &smi_infos, link) { >>> @@ -2436,6 +2437,7 @@ int ipmi_si_remove_by_dev(struct device *dev) >>>           } >>>       } >>>       mutex_unlock(&smi_infos_lock); >>> +    kfree(pdev->driver_override); >>>         return rv; >>>   } >> >> >> >> . >> > >