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Wed, 28 Oct 2020 10:09:23 -0800 Received: from mtkmbs08n2.mediatek.inc (172.21.101.56) by MTKMBS62N1.mediatek.inc (172.29.193.41) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 28 Oct 2020 10:59:20 -0700 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs08n2.mediatek.inc (172.21.101.56) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 29 Oct 2020 01:59:13 +0800 Received: from [172.21.77.33] (172.21.77.33) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Thu, 29 Oct 2020 01:59:13 +0800 Message-ID: <1603907954.21794.1.camel@mtkswgap22> Subject: Re: [PATCH v2] usb: gadget: configfs: Fix use-after-free issue with udc_name From: Macpaul Lin To: Date: Thu, 29 Oct 2020 01:59:14 +0800 In-Reply-To: <1603907723-19499-1-git-send-email-macpaul.lin@mediatek.com> References: <1603907723-19499-1-git-send-email-macpaul.lin@mediatek.com> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-TM-SNTS-SMTP: 6FF4D9C7666B2DA439629EFF15D866C8945F8FB2572A70F92FE3680A91FDC8B62000:8 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201028_140927_831564_FA61298A X-CRM114-Status: GOOD ( 19.77 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-usb@vger.kernel.org, Mediatek WSD Upstream , eddie.hung@mediatek.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux-mediatek@lists.infradead.org, Ainge Hsu , chunfeng.yun@mediatek.com, Macpaul Lin , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, 2020-10-29 at 01:55 +0800, Macpaul Lin wrote: > From: Eddie Hung > > There is a use-after-free issue, if access udc_name > in function gadget_dev_desc_UDC_store after another context > free udc_name in function unregister_gadget. > > Context 1: > gadget_dev_desc_UDC_store()->unregister_gadget()-> > free udc_name->set udc_name to NULL > > Context 2: > gadget_dev_desc_UDC_show()-> access udc_name > > Call trace: > dump_backtrace+0x0/0x340 > show_stack+0x14/0x1c > dump_stack+0xe4/0x134 > print_address_description+0x78/0x478 > __kasan_report+0x270/0x2ec > kasan_report+0x10/0x18 > __asan_report_load1_noabort+0x18/0x20 > string+0xf4/0x138 > vsnprintf+0x428/0x14d0 > sprintf+0xe4/0x12c > gadget_dev_desc_UDC_show+0x54/0x64 > configfs_read_file+0x210/0x3a0 > __vfs_read+0xf0/0x49c > vfs_read+0x130/0x2b4 > SyS_read+0x114/0x208 > el0_svc_naked+0x34/0x38 > > Add mutex_lock to protect this kind of scenario. > > Signed-off-by: Eddie Hung > Signed-off-by: Macpaul Lin > Reviewed-by: Peter Chen > Cc: stable@vger.kernel.org > --- > Changes for v2: > - Fix typo %s/contex/context, Thanks Peter. > > drivers/usb/gadget/configfs.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c > index 56051bb..d9743f4 100644 > --- a/drivers/usb/gadget/configfs.c > +++ b/drivers/usb/gadget/configfs.c > @@ -221,9 +221,16 @@ static ssize_t gadget_dev_desc_bcdUSB_store(struct config_item *item, > > static ssize_t gadget_dev_desc_UDC_show(struct config_item *item, char *page) > { > - char *udc_name = to_gadget_info(item)->composite.gadget_driver.udc_name; > + struct gadget_info *gi = to_gadget_info(item); > + char *udc_name; > + int ret; > + > + mutex_lock(&gi->lock); > + udc_name = gi->composite.gadget_driver.udc_name; > + ret = sprintf(page, "%s\n", udc_name ?: ""); > + mutex_unlock(&gi->lock); > > - return sprintf(page, "%s\n", udc_name ?: ""); > + return ret; > } > > static int unregister_gadget(struct gadget_info *gi) Sorry, it looks like still a base64 encoded mail. I'll feedback to our IT department again. Please ignore this mail. Thanks Macpaul Lin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel