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[92.176.231.205]) by smtp.gmail.com with ESMTPSA id f7-20020a0560001b0700b0021d68e1fd42sm6255192wrz.89.2022.07.05.03.02.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Jul 2022 03:02:35 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Cc: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Peter Robinson , Thomas Zimmermann , Javier Martinez Canillas , Daniel Vetter , David Airlie , Maarten Lankhorst , Maxime Ripard , dri-devel@lists.freedesktop.org Subject: [PATCH v2 1/2] drm: Use size_t type for len variable in drm_copy_field() Date: Tue, 5 Jul 2022 12:02:13 +0200 Message-Id: <20220705100215.572498-2-javierm@redhat.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220705100215.572498-1-javierm@redhat.com> References: <20220705100215.572498-1-javierm@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The strlen() function returns a size_t which is an unsigned int on 32-bit arches and an unsigned long on 64-bit arches. But in the drm_copy_field() function, the strlen() return value is assigned to an 'int len' variable. Later, the len variable is passed as copy_from_user() third argument that is an unsigned long parameter as well. In theory, this can lead to an integer overflow via type conversion. Since the assignment happens to a signed int lvalue instead of a size_t lvalue. In practice though, that's unlikely since the values copied are set by DRM drivers and not controlled by userspace. But using a size_t for len is the correct thing to do anyways. Signed-off-by: Javier Martinez Canillas Tested-by: Peter Robinson Reviewed-by: Thomas Zimmermann --- Changes in v2: - Add Peter Robinson Tested-by and Thomas Zimmermann Reviewed-by tags. drivers/gpu/drm/drm_ioctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index 8faad23dc1d8..e1b9a03e619c 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -472,7 +472,7 @@ EXPORT_SYMBOL(drm_invalid_op); */ static int drm_copy_field(char __user *buf, size_t *buf_len, const char *v= alue) { - int len; + size_t len; =20 /* don't overflow userbuf */ len =3D strlen(value); --=20 2.36.1 From nobody Sun Apr 19 07:16:43 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4D233C43334 for ; Tue, 5 Jul 2022 10:02:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232123AbiGEKCu (ORCPT ); Tue, 5 Jul 2022 06:02:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56418 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231765AbiGEKCn (ORCPT ); Tue, 5 Jul 2022 06:02:43 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0112F13E96 for ; Tue, 5 Jul 2022 03:02:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657015361; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PXp75we4g7tfDLKjBv7MZGhsHN2tTZVGENMsoYt5xd8=; b=P6xfMkMPDd80CnI3E5yK2oVFixRYslDyPh5aN5XidoFuYS0qq8fOrDcsO3GZRET5lRUfKb 2+7oXVJdw+3cwUQWUUuYUu26myVOO6NsDd1z616n5LuCmX+YBM9zgDQdIpgP4NiXiQG7hW uJwUZNaAjDH5pxbTVW1WAIPo7ob1NYc= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-435-sBUIYV7SOFCgX6KVQWl3QQ-1; Tue, 05 Jul 2022 06:02:40 -0400 X-MC-Unique: sBUIYV7SOFCgX6KVQWl3QQ-1 Received: by mail-wm1-f70.google.com with SMTP id j35-20020a05600c1c2300b003a167dfa0ecso6547738wms.5 for ; Tue, 05 Jul 2022 03:02:40 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=PXp75we4g7tfDLKjBv7MZGhsHN2tTZVGENMsoYt5xd8=; b=BP9a8Z8bnwOEDcur32eMRckaVuhw2uG9UkZXE24+kAfbhY0xIrR04FHALgNJTejmnd KEy22v4QcoaiW5s1W1BgfJNLOVbzBSFsD8A/XgT2mAftgizJ9YJE2ioMtGBES2a4A30B IGNGW/uefks7puMT0VRvR7PoG+HQnMT1CE1aqKKXQPlhOUI4TjxpuEvfVQdcZ895kpLg ZaFQ8Dsjj/pPBIKcWCR6rNebfqFEed0wNKZxTtSMIsAj+19HWT8amfempg2T+E3of8VD oC357eTVUfWZHtKJr5bB9zZvSoiFL7HvXDgN/yS7YsNs+zpEuUeRi/+2X+sLQGqNpoOr MVZQ== X-Gm-Message-State: AJIora/6e9N10Y3K20nIUZYxlp/LvGvqJ4ovYTPh5yylUAwYhZ7QkR6u T2CCsQwm8mFR7KDhFVWnAYCMUxYa4UDdg4CSUzgYF4u7LN2AImMGO8fjYfbYafhng5uaph2aFrS 90GLwJmW3nwLcIn2u3sgg9LiAL30jkYTLNsUinwh+A+SeBC16K0q5HZ5gS/c/mdzdtbnmCzz87x I= X-Received: by 2002:adf:f84a:0:b0:21d:6e52:7957 with SMTP id d10-20020adff84a000000b0021d6e527957mr5815176wrq.252.1657015357858; Tue, 05 Jul 2022 03:02:37 -0700 (PDT) X-Google-Smtp-Source: AGRyM1vZWSLJ9APoFLLcARii/p9DrogtNdYkpeeiX/0eZqF0i0sAWYJXINSPuRKOHdGqmknYrdkgDA== X-Received: by 2002:adf:f84a:0:b0:21d:6e52:7957 with SMTP id d10-20020adff84a000000b0021d6e527957mr5815138wrq.252.1657015357593; Tue, 05 Jul 2022 03:02:37 -0700 (PDT) Received: from minerva.home (205.pool92-176-231.dynamic.orange.es. [92.176.231.205]) by smtp.gmail.com with ESMTPSA id f7-20020a0560001b0700b0021d68e1fd42sm6255192wrz.89.2022.07.05.03.02.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Jul 2022 03:02:37 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Cc: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Peter Robinson , Thomas Zimmermann , Javier Martinez Canillas , Daniel Vetter , David Airlie , Maarten Lankhorst , Maxime Ripard , dri-devel@lists.freedesktop.org Subject: [PATCH v2 2/2] drm: Prevent drm_copy_field() to attempt copying a NULL pointer Date: Tue, 5 Jul 2022 12:02:14 +0200 Message-Id: <20220705100215.572498-3-javierm@redhat.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220705100215.572498-1-javierm@redhat.com> References: <20220705100215.572498-1-javierm@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" There are some struct drm_driver fields that are required by drivers since drm_copy_field() attempts to copy them to user-space via DRM_IOCTL_VERSION. But it can be possible that a driver has a bug and did not set some of the fields, which leads to drm_copy_field() attempting to copy a NULL pointer: [ +10.395966] Unable to handle kernel access to user memory outside uaccess= routines at virtual address 0000000000000000 [ +0.010955] Mem abort info: [ +0.002835] ESR =3D 0x0000000096000004 [ +0.003872] EC =3D 0x25: DABT (current EL), IL =3D 32 bits [ +0.005395] SET =3D 0, FnV =3D 0 [ +0.003113] EA =3D 0, S1PTW =3D 0 [ +0.003182] FSC =3D 0x04: level 0 translation fault [ +0.004964] Data abort info: [ +0.002919] ISV =3D 0, ISS =3D 0x00000004 [ +0.003886] CM =3D 0, WnR =3D 0 [ +0.003040] user pgtable: 4k pages, 48-bit VAs, pgdp=3D0000000115dad000 [ +0.006536] [0000000000000000] pgd=3D0000000000000000, p4d=3D000000000000= 0000 [ +0.006925] Internal error: Oops: 96000004 [#1] SMP ... [ +0.011113] pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE= =3D--) [ +0.007061] pc : __pi_strlen+0x14/0x150 [ +0.003895] lr : drm_copy_field+0x30/0x1a4 [ +0.004156] sp : ffff8000094b3a50 [ +0.003355] x29: ffff8000094b3a50 x28: ffff8000094b3b70 x27: 000000000000= 0040 [ +0.007242] x26: ffff443743c2ba00 x25: 0000000000000000 x24: 000000000000= 0040 [ +0.007243] x23: ffff443743c2ba00 x22: ffff8000094b3b70 x21: 000000000000= 0000 [ +0.007241] x20: 0000000000000000 x19: ffff8000094b3b90 x18: 000000000000= 0000 [ +0.007241] x17: 0000000000000000 x16: 0000000000000000 x15: 0000aaab14b9= af40 [ +0.007241] x14: 0000000000000000 x13: 0000000000000000 x12: 000000000000= 0000 [ +0.007239] x11: 0000000000000000 x10: 0000000000000000 x9 : ffffa524ad67= d4d8 [ +0.007242] x8 : 0101010101010101 x7 : 7f7f7f7f7f7f7f7f x6 : 6c6e6263606e= 7141 [ +0.007239] x5 : 0000000000000000 x4 : 0000000000000000 x3 : 000000000000= 0000 [ +0.007241] x2 : 0000000000000000 x1 : ffff8000094b3b90 x0 : 000000000000= 0000 [ +0.007240] Call trace: [ +0.002475] __pi_strlen+0x14/0x150 [ +0.003537] drm_version+0x84/0xac [ +0.003448] drm_ioctl_kernel+0xa8/0x16c [ +0.003975] drm_ioctl+0x270/0x580 [ +0.003448] __arm64_sys_ioctl+0xb8/0xfc [ +0.003978] invoke_syscall+0x78/0x100 [ +0.003799] el0_svc_common.constprop.0+0x4c/0xf4 [ +0.004767] do_el0_svc+0x38/0x4c [ +0.003357] el0_svc+0x34/0x100 [ +0.003185] el0t_64_sync_handler+0x11c/0x150 [ +0.004418] el0t_64_sync+0x190/0x194 [ +0.003716] Code: 92402c04 b200c3e8 f13fc09f 5400088c (a9400c02) [ +0.006180] ---[ end trace 0000000000000000 ]--- Reported-by: Peter Robinson Signed-off-by: Javier Martinez Canillas --- Changes in v2: - Just warn if a value isn't set and report it as a string of length 0. (Thomas Zimmermann). drivers/gpu/drm/drm_ioctl.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index e1b9a03e619c..ca2a6e6101dc 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -474,6 +474,12 @@ static int drm_copy_field(char __user *buf, size_t *bu= f_len, const char *value) { size_t len; =20 + /* don't attempt to copy a NULL pointer */ + if (WARN_ONCE(!value, "BUG: the value to copy was not set!")) { + *buf_len =3D 0; + return 0; + } + /* don't overflow userbuf */ len =3D strlen(value); if (len > *buf_len) --=20 2.36.1