From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E508413AEA for ; Sun, 9 Jul 2023 15:16:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83851C433CD; Sun, 9 Jul 2023 15:16:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1688915811; bh=nTYRnmB0100wh1J1+ZWj878exMeOb0t/OxCjUY+Jk5g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aka/h7pr7kPKpthF9zvrvKm3vCmM9w32qI/6WB3FyzFNwQZRKW5kTC7O6mkEKcdRM R4vYF4coGXq1gAiWi7DCjsuMkZKsWA3adxZuzYPCSVgOg7aL2ADRn348wJnvdSgZd1 oGMO59zHFftCvkEdKU4HIcO8MJKWXMK1YXAiPccIp5o6TEXovvuKAACvwXglB427GT SLUKdj9XiFktz2TUvF9UVytMwYPzMIfjyO/Apsv1qE//HVUKNefZ2VpN+3kJqgy17f q/NP9hF/Fv9Il5umI3pX6FIplAiieoeMe3hh59NsRvHuezpcV+ylP4qnc3H6UxCyiQ RQYBzchMY9OiQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Gustavo A. R. Silva" , Simon Horman , Johannes Berg , Sasha Levin , johannes@sipsolutions.net, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, linux-wireless@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 3/4] wifi: wext-core: Fix -Wstringop-overflow warning in ioctl_standard_iw_point() Date: Sun, 9 Jul 2023 11:16:43 -0400 Message-Id: <20230709151645.514172-3-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230709151645.514172-1-sashal@kernel.org> References: <20230709151645.514172-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 4.14.320 Content-Transfer-Encoding: 8bit From: "Gustavo A. R. Silva" [ Upstream commit 71e7552c90db2a2767f5c17c7ec72296b0d92061 ] -Wstringop-overflow is legitimately warning us about extra_size pontentially being zero at some point, hence potenially ending up _allocating_ zero bytes of memory for extra pointer and then trying to access such object in a call to copy_from_user(). Fix this by adding a sanity check to ensure we never end up trying to allocate zero bytes of data for extra pointer, before continue executing the rest of the code in the function. Address the following -Wstringop-overflow warning seen when built m68k architecture with allyesconfig configuration: from net/wireless/wext-core.c:11: In function '_copy_from_user', inlined from 'copy_from_user' at include/linux/uaccess.h:183:7, inlined from 'ioctl_standard_iw_point' at net/wireless/wext-core.c:825:7: arch/m68k/include/asm/string.h:48:25: warning: '__builtin_memset' writing 1 or more bytes into a region of size 0 overflows the destination [-Wstringop-overflow=] 48 | #define memset(d, c, n) __builtin_memset(d, c, n) | ^~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/uaccess.h:153:17: note: in expansion of macro 'memset' 153 | memset(to + (n - res), 0, res); | ^~~~~~ In function 'kmalloc', inlined from 'kzalloc' at include/linux/slab.h:694:9, inlined from 'ioctl_standard_iw_point' at net/wireless/wext-core.c:819:10: include/linux/slab.h:577:16: note: at offset 1 into destination object of size 0 allocated by '__kmalloc' 577 | return __kmalloc(size, flags); | ^~~~~~~~~~~~~~~~~~~~~~ This help with the ongoing efforts to globally enable -Wstringop-overflow. Link: https://github.com/KSPP/linux/issues/315 Signed-off-by: Gustavo A. R. Silva Reviewed-by: Simon Horman Link: https://lore.kernel.org/r/ZItSlzvIpjdjNfd8@work Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin --- net/wireless/wext-core.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c index b6414c7bef556..4bf33f9b28870 100644 --- a/net/wireless/wext-core.c +++ b/net/wireless/wext-core.c @@ -798,6 +798,12 @@ static int ioctl_standard_iw_point(struct iw_point *iwp, unsigned int cmd, } } + /* Sanity-check to ensure we never end up _allocating_ zero + * bytes of data for extra. + */ + if (extra_size <= 0) + return -EFAULT; + /* kzalloc() ensures NULL-termination for essid_compat. */ extra = kzalloc(extra_size, GFP_KERNEL); if (!extra) -- 2.39.2