From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: [PATCH AUTOSEL 4.20 078/105] pvcalls-front: fix potential null dereference Date: Tue, 12 Feb 2019 21:33:09 -0500 Message-ID: <20190213023336.19019-78-sashal@kernel.org> References: <20190213023336.19019-1-sashal@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1gtkOh-0000Cm-Jn for xen-devel@lists.xenproject.org; Wed, 13 Feb 2019 02:35:39 +0000 In-Reply-To: <20190213023336.19019-1-sashal@kernel.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Juergen Gross , Sasha Levin , Stefano Stabellini , xen-devel@lists.xenproject.org, Boris Ostrovsky , Wen Yang , Dan 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S2388047AbfBMCfj (ORCPT ); Tue, 12 Feb 2019 21:35:39 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 74EB1222CD; Wed, 13 Feb 2019 02:35:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550025338; bh=hudbPPq2wsnn673GkKZ6TJB4xcclMV3mS4tVqlm3Mow=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nII3WzL4gQkE2ym8i4D3Li3Junntrcr5SxW+BjUUOINEKGJA+GxmHXQOL3VlNDJVL /juWM+W0ADxJE/XwCEw5W+R5M0dninMYTIKXP2pzrvYVBAMsi7m+rK/gG+KxWukv9l BX5NwHgiAbeLZnuf50Ac7KbcllCRqFb0PPxSStfU= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Wen Yang , Boris Ostrovsky , Juergen Gross , Stefano Stabellini , Dan Carpenter , xen-devel@lists.xenproject.org, Sasha Levin Subject: [PATCH AUTOSEL 4.20 078/105] pvcalls-front: fix potential null dereference Date: Tue, 12 Feb 2019 21:33:09 -0500 Message-Id: <20190213023336.19019-78-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190213023336.19019-1-sashal@kernel.org> References: <20190213023336.19019-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wen Yang [ Upstream commit b4711098066f1cf808d4dc11a1a842860a3292fe ] static checker warning: drivers/xen/pvcalls-front.c:373 alloc_active_ring() error: we previously assumed 'map->active.ring' could be null (see line 357) drivers/xen/pvcalls-front.c 351 static int alloc_active_ring(struct sock_mapping *map) 352 { 353 void *bytes; 354 355 map->active.ring = (struct pvcalls_data_intf *) 356 get_zeroed_page(GFP_KERNEL); 357 if (!map->active.ring) ^^^^^^^^^^^^^^^^^ Check 358 goto out; 359 360 map->active.ring->ring_order = PVCALLS_RING_ORDER; 361 bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 362 PVCALLS_RING_ORDER); 363 if (!bytes) 364 goto out; 365 366 map->active.data.in = bytes; 367 map->active.data.out = bytes + 368 XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER); 369 370 return 0; 371 372 out: --> 373 free_active_ring(map); ^^^ Add null check on map->active.ring before dereferencing it to avoid any NULL pointer dereferences. Fixes: 9f51c05dc41a ("pvcalls-front: Avoid get_free_pages(GFP_KERNEL) under spinlock") Reported-by: Dan Carpenter Suggested-by: Boris Ostrovsky Signed-off-by: Wen Yang Reviewed-by: Boris Ostrovsky CC: Boris Ostrovsky CC: Juergen Gross CC: Stefano Stabellini CC: Dan Carpenter CC: xen-devel@lists.xenproject.org CC: linux-kernel@vger.kernel.org Signed-off-by: Boris Ostrovsky Signed-off-by: Sasha Levin --- drivers/xen/pvcalls-front.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c index 6357160d466a..91da7e44d5d4 100644 --- a/drivers/xen/pvcalls-front.c +++ b/drivers/xen/pvcalls-front.c @@ -343,6 +343,9 @@ int pvcalls_front_socket(struct socket *sock) static void free_active_ring(struct sock_mapping *map) { + if (!map->active.ring) + return; + free_pages((unsigned long)map->active.data.in, map->active.ring->ring_order); free_page((unsigned long)map->active.ring); -- 2.19.1