From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753260AbaHTXKW (ORCPT ); Wed, 20 Aug 2014 19:10:22 -0400 Received: from casper.infradead.org ([85.118.1.10]:47303 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752846AbaHTXKV (ORCPT ); Wed, 20 Aug 2014 19:10:21 -0400 Message-ID: <1408576214.9540.2.camel@infradead.org> Subject: Re: [PATCH] params: fix potential memory leak in add_sysfs_param() From: David Woodhouse To: "rusty@rustcorp.com.au" Cc: "arjun024@gmail.com" , "torvalds@linux-foundation.org" , "linux-kernel@vger.kernel.org" , "jg1.han@samsung.com" , "akpm@linux-foundation.org" Date: Wed, 20 Aug 2014 18:10:14 -0500 In-Reply-To: <1408573066.9484.11.camel@intel.com> References: <1408564816-1778-1-git-send-email-arjun024@gmail.com> <87mwayj39c.fsf@rustcorp.com.au> <87ha16izpu.fsf@rustcorp.com.au> <1408573066.9484.11.camel@intel.com> Content-Type: multipart/signed; micalg="sha-1"; protocol="application/x-pkcs7-signature"; boundary="=-8FTKF5fDrDRDwdiFFbMh" X-Mailer: Evolution 3.12.5 (3.12.5-1.fc20) Mime-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-8FTKF5fDrDRDwdiFFbMh Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2014-08-20 at 22:17 +0000, Woodhouse, David wrote: >=20 > Except that in the failure case we *free* the old mk->mp and never free > mk->mp->grp.attrs so it *is* indeed lost. >=20 > A simpler version of Arjun's patch might look like this: >=20 > diff --git a/kernel/params.c b/kernel/params.c > index 34f5270..f9459bc 100644 > --- a/kernel/params.c > +++ b/kernel/params.c > @@ -613,7 +613,6 @@ static __modinit int add_sysfs_param(struct module_ko= bject *mk, > sizeof(*mk->mp) + sizeof(mk->mp->attrs[0]) * (num+= 1), > GFP_KERNEL); > if (!new) { > - kfree(attrs); > err =3D -ENOMEM; > goto fail; > } > @@ -653,7 +652,10 @@ static __modinit int add_sysfs_param(struct module_k= object *mk, > fail_free_new: > kfree(new); > fail: > - mk->mp =3D NULL; > + if (mk->mp) { > + kfree(mk->mp->grp.attrs); > + mk->mp =3D NULL; > + } > return err; > } Of course this and Arjun's original *both* fail to fix the classic bug in the 'new =3D krealloc(mk->mp=E2=80=A6)' bit, failing to free the old mk-= >mp if the realloc fails. I think my alternative fix that didn't kill the old params is probably the better way forward. --=20 dwmw2 --=-8FTKF5fDrDRDwdiFFbMh Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIISxDCCBjQw ggQcoAMCAQICAR4wDQYJKoZIhvcNAQEFBQAwfTELMAkGA1UEBhMCSUwxFjAUBgNVBAoTDVN0YXJ0 Q29tIEx0ZC4xKzApBgNVBAsTIlNlY3VyZSBEaWdpdGFsIENlcnRpZmljYXRlIFNpZ25pbmcxKTAn BgNVBAMTIFN0YXJ0Q29tIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MB4XDTA3MTAyNDIxMDE1NVoX DTE3MTAyNDIxMDE1NVowgYwxCzAJBgNVBAYTAklMMRYwFAYDVQQKEw1TdGFydENvbSBMdGQuMSsw KQYDVQQLEyJTZWN1cmUgRGlnaXRhbCBDZXJ0aWZpY2F0ZSBTaWduaW5nMTgwNgYDVQQDEy9TdGFy dENvbSBDbGFzcyAxIFByaW1hcnkgSW50ZXJtZWRpYXRlIENsaWVudCBDQTCCASIwDQYJKoZIhvcN AQEBBQADggEPADCCAQoCggEBAMcJg8zOLdgasSmkLhOrlr6KMoOMpohBllVHrdRvEg/q6r8jR+EK 75xCGhR8ToREoqe7zM9/UnC6TS2y9UKTpT1v7RSMzR0t6ndl0TWBuUr/UXBhPk+Kmy7bI4yW4urC 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