From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753955AbeAQRHA (ORCPT ); Wed, 17 Jan 2018 12:07:00 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:4654 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752806AbeAQRG7 (ORCPT ); Wed, 17 Jan 2018 12:06:59 -0500 Subject: Re: [PATCH] ipmi: use dynamic memory for DMI driver override To: , References: <1516207017-158659-1-git-send-email-john.garry@huawei.com> CC: , From: John Garry Message-ID: <691ee7e1-89fd-2f9f-9b69-1c040ea77c12@huawei.com> Date: Wed, 17 Jan 2018 17:06:30 +0000 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.238] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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; >> } > > > > . >