From patchwork Wed Oct 25 10:34:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Dominique Martinet X-Patchwork-Id: 13435960 Received: from nautica.notk.org (nautica.notk.org [91.121.71.147]) (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 B6AEA266BC for ; Wed, 25 Oct 2023 10:35:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=codewreck.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=codewreck.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=codewreck.org header.i=@codewreck.org header.b="V4ob44En"; dkim=pass (2048-bit key) header.d=codewreck.org header.i=@codewreck.org header.b="ZurXGHQv" Received: by nautica.notk.org (Postfix, from userid 108) id 1F8C9C02C; Wed, 25 Oct 2023 12:35:06 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codewreck.org; s=2; t=1698230106; bh=alDC8/pUNCLU3G+aaZxX11BvuNObZgKMGq1KaeSAe4U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V4ob44EnsAlv0DLYwv9MwUWumioP+1pIvVZpDstuu8eObyIa4eA3vphY/AUy6WNaH 56lu/BH36rs54EWmAVP0tZisDWrTMrJvYbiZBTX+o7XXrgGXDs0zTgC+PMHujZfBuL M7aCnF7gakPNQ8+5IxQWF+1RhuKQn84lwIrm3izRxcvpZjOV/+AuQ6/c4oKxc6yx95 ICCQR5m0kVo8c9o4E9VGF4rjzFEpu00+AD+bzpnFeorprOYfN7qu5HEW7YX2ZLiSKV LwV1Lbp/b111+VPEJdEDLO0WDB3ICbFcOnNes4GfC0gPecqFMUhZ5Dimdbm1Jv3Izn 24ozAh7TAi0wQ== X-Spam-Level: Received: from gaia (localhost [127.0.0.1]) by nautica.notk.org (Postfix) with ESMTPS id CECA9C01F; Wed, 25 Oct 2023 12:35:00 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codewreck.org; s=2; t=1698230104; bh=alDC8/pUNCLU3G+aaZxX11BvuNObZgKMGq1KaeSAe4U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZurXGHQvdNpON1tO8sq6IhplF33P2ECIOGjNuOPLKzS3T3SiYIhcGnsoVAUANBEN6 o2JyvYYypXjt9XM1yLBG4txzkVOtzYBrVGbCtB0h+BdZv5ATm70fEPRiYIy7BXjqCC mtFxmd2jvWnD3hrfq62FSomadTMiFdZm7e//dwSUGeWPuC17aVbdWWElUKFTvmfKMC AsjuaCkZX5WoZ9sVvBjWF0wePWH8ItH+HDI6nYzOQ4oWxQNmBcBP4ZGuW7Sr4QPx+y XFrd+cr0roJ9+NdbuWYhxiFMIuCoMwbKokAm9RgeFdGUO+L0saDYpoW7I9tz/5P8BL yYdyaUtmLp6UQ== Received: from gaia.codewreck.org (localhost.lan [::1]) by gaia (OpenSMTPD) with ESMTP id c2b62181; Wed, 25 Oct 2023 10:34:53 +0000 (UTC) From: Dominique Martinet To: v9fs@lists.linux.dev Cc: ericvh@kernel.org, linux_oss@crudebyte.com, lucho@ionkov.net, linux-kernel@vger.kernel.org, Dominique Martinet Subject: [PATCH v2 3/3] 9p/net: xen: fix false positive printf format overflow warning Date: Wed, 25 Oct 2023 19:34:45 +0900 Message-ID: <20231025103445.1248103-3-asmadeus@codewreck.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231025103445.1248103-1-asmadeus@codewreck.org> References: <20231025103445.1248103-1-asmadeus@codewreck.org> Precedence: bulk X-Mailing-List: v9fs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Use the constant to make the compiler happy about this warning: net/9p/trans_xen.c: In function ‘xen_9pfs_front_changed’: net/9p/trans_xen.c:444:39: warning: ‘%d’ directive writing between 1 and 11 bytes into a region of size 8 [-Wformat-overflow=] 444 | sprintf(str, "ring-ref%d", i); | ^~ In function ‘xen_9pfs_front_init’, inlined from ‘xen_9pfs_front_changed’ at net/9p/trans_xen.c:516:8, inlined from ‘xen_9pfs_front_changed’ at net/9p/trans_xen.c:504:13: net/9p/trans_xen.c:444:30: note: directive argument in the range [-2147483644, 2147483646] 444 | sprintf(str, "ring-ref%d", i); | ^~~~~~~~~~~~ net/9p/trans_xen.c:444:17: note: ‘sprintf’ output between 10 and 20 bytes into a destination of size 16 444 | sprintf(str, "ring-ref%d", i); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ net/9p/trans_xen.c: In function ‘xen_9pfs_front_changed’: net/9p/trans_xen.c:450:45: warning: ‘%d’ directive writing between 1 and 11 bytes into a region of size 2 [-Wformat-overflow=] 450 | sprintf(str, "event-channel-%d", i); | ^~ In function ‘xen_9pfs_front_init’, inlined from ‘xen_9pfs_front_changed’ at net/9p/trans_xen.c:516:8, inlined from ‘xen_9pfs_front_changed’ at net/9p/trans_xen.c:504:13: net/9p/trans_xen.c:450:30: note: directive argument in the range [-2147483644, 2147483646] 450 | sprintf(str, "event-channel-%d", i); | ^~~~~~~~~~~~~~~~~~ net/9p/trans_xen.c:450:17: note: ‘sprintf’ output between 16 and 26 bytes into a destination of size 16 450 | sprintf(str, "event-channel-%d", i); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ There is no change in logic: there only are a constant number of rings, and there also already is a BUILD_BUG_ON that checks if that constant goes over 9 as anything bigger would no longer fit the event-channel-%d destination size. In theory having that size as part of the struct means it could be modified by another thread and makes the compiler lose track of possible values for 'i' here, using the constant directly here makes it work. Signed-off-by: Dominique Martinet Message-ID: <20231023233704.1185154-4-asmadeus@codewreck.org> Reviewed-by: Christian Schoenebeck --- v1->v2: - use constant directly instead of going through a local variable net/9p/trans_xen.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c index 1fffe2bed5b0..dfdbe1ca5338 100644 --- a/net/9p/trans_xen.c +++ b/net/9p/trans_xen.c @@ -54,7 +54,6 @@ struct xen_9pfs_front_priv { char *tag; struct p9_client *client; - int num_rings; struct xen_9pfs_dataring *rings; }; @@ -131,7 +130,7 @@ static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req) if (list_entry_is_head(priv, &xen_9pfs_devs, list)) return -EINVAL; - num = p9_req->tc.tag % priv->num_rings; + num = p9_req->tc.tag % XEN_9PFS_NUM_RINGS; ring = &priv->rings[num]; again: @@ -279,7 +278,7 @@ static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv) list_del(&priv->list); write_unlock(&xen_9pfs_lock); - for (i = 0; i < priv->num_rings; i++) { + for (i = 0; i < XEN_9PFS_NUM_RINGS; i++) { struct xen_9pfs_dataring *ring = &priv->rings[i]; cancel_work_sync(&ring->work); @@ -408,15 +407,14 @@ static int xen_9pfs_front_init(struct xenbus_device *dev) if (p9_xen_trans.maxsize > XEN_FLEX_RING_SIZE(max_ring_order)) p9_xen_trans.maxsize = XEN_FLEX_RING_SIZE(max_ring_order) / 2; - priv->num_rings = XEN_9PFS_NUM_RINGS; - priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings), + priv->rings = kcalloc(XEN_9PFS_NUM_RINGS, sizeof(*priv->rings), GFP_KERNEL); if (!priv->rings) { kfree(priv); return -ENOMEM; } - for (i = 0; i < priv->num_rings; i++) { + for (i = 0; i < XEN_9PFS_NUM_RINGS; i++) { priv->rings[i].priv = priv; ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i], max_ring_order); @@ -434,10 +432,11 @@ static int xen_9pfs_front_init(struct xenbus_device *dev) if (ret) goto error_xenbus; ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u", - priv->num_rings); + XEN_9PFS_NUM_RINGS); if (ret) goto error_xenbus; - for (i = 0; i < priv->num_rings; i++) { + + for (i = 0; i < XEN_9PFS_NUM_RINGS; i++) { char str[16]; BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9);