From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from r3-20.sinamail.sina.com.cn (r3-20.sinamail.sina.com.cn [202.108.3.20]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C030A17D6 for ; Wed, 15 Apr 2026 00:33:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.108.3.20 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776213229; cv=none; b=Zg4aJIzbjTS1rQ6xSnLZdO/HOo2DoL9DrTF7iNG/1N8FjxLlfE5CXsrnjpt/wIz62ZiPmDujK+9CIk1il5DzCVUlACmiQi5m5amEltKyR3Z9nE/gKXmbH58Omc6hNlMEKm7qmWMWpaiQ9lAVXTLN9DEWTBTTQISnEwx755QZmpE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776213229; c=relaxed/simple; bh=BT9dvd2lbTba9OtQ/KcXWDlNOM1SH36KUZhSrn/qhn4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aOh0MavF1mwUs+YuyGr+gxkeUiAp8Mhn+Zklejdy+XDd5RPA+kx+1UB/JSyYOoTyUJl64/qHYTaXdTZvoSNfVyrQ6qABc61WhG+3X0NJ1Gz3YVLvriMTjifXtWax3ZEqeqZZjRAaZkQ69xHLH4qt9+4W6DXIHIYdiQHttV9BVzI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=DF2eb/Cn; arc=none smtp.client-ip=202.108.3.20 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="DF2eb/Cn" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1776213225; bh=5mL98cJq8UODba+027b3KEYcrB++wReTqGIWhN0uEXQ=; h=From:Subject:Date:Message-ID; b=DF2eb/Cny7MdSJdUsxCher+8ghevKezAEQZ3HTDnVuwEuZz9aS0mk/YCjOZp67gFL 0wsPVcYnH7lxLu6Y+RYGgCAKUWlOmHiBeWegy5OJ3j17aR/TEEy6Tx++BDNH7UtlCU 35WS9H1RxLgMZTaFLvcignaNN1aDfQbH2IOJOXW4= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.249.62.144]) by sina.com (10.54.253.32) with ESMTP id 69DEDCDC0000192A; Wed, 15 Apr 2026 08:33:35 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=hdanton@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=hdanton@sina.com X-SMAIL-MID: 3830414456879 X-SMAIL-UIID: 13CE7FFD168E4C6EAE09C95D7EFE78F7-20260415-083335-1 From: Hillf Danton To: syzbot Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [dri?] KASAN: slab-use-after-free Read in drm_gem_object_release_handle Date: Wed, 15 Apr 2026 08:33:21 +0800 Message-ID: <20260415003322.1854-1-hdanton@sina.com> In-Reply-To: <69dd24f4.a00a0220.468cb.004a.GAE@google.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > Date: Mon, 13 Apr 2026 10:16:36 -0700 [thread overview] > Hello, > > syzbot found the following issue on: > > HEAD commit: f5459048c38a Merge tag 'i2c-for-7.0-final' of git://git.ke.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1028d106580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=6754c86e8d9e4c91 > dashboard link: https://syzkaller.appspot.com/bug?extid=b2e951687503f32f74ce > compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1428d106580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17509036580000 #syz test --- x/drivers/gpu/drm/drm_gem.c +++ y/drivers/gpu/drm/drm_gem.c @@ -404,7 +404,8 @@ drm_gem_handle_delete(struct drm_file *f spin_lock(&filp->table_lock); /* Check if we currently have a reference on the object */ - obj = idr_replace(&filp->object_idr, NULL, handle); + obj = idr_find(&filp->object_idr, handle); + idr_remove(&filp->object_idr, handle); spin_unlock(&filp->table_lock); if (IS_ERR_OR_NULL(obj)) return -EINVAL; @@ -412,11 +413,6 @@ drm_gem_handle_delete(struct drm_file *f /* Release driver's reference and decrement refcount. */ drm_gem_object_release_handle(handle, obj, filp); - /* And finally make the handle available for future allocations. */ - spin_lock(&filp->table_lock); - idr_remove(&filp->object_idr, handle); - spin_unlock(&filp->table_lock); - return 0; } EXPORT_SYMBOL(drm_gem_handle_delete); @@ -1085,8 +1081,20 @@ drm_gem_open(struct drm_device *dev, str void drm_gem_release(struct drm_device *dev, struct drm_file *file_private) { - idr_for_each(&file_private->object_idr, - &drm_gem_object_release_handle, file_private); + struct drm_gem_object *obj; + int id; + + for (;;) { + id = 0; + spin_lock(&file_private->table_lock); + obj = idr_get_next(&file_private->object_idr, &id); + if (obj) + idr_remove(&file_private->object_idr, id); + spin_unlock(&file_private->table_lock); + if (!obj) + break; + drm_gem_object_release_handle(id, obj, file_private); + } idr_destroy(&file_private->object_idr); } --