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 F0A4B28FE; Sat, 30 Dec 2023 12:05:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ObgGSyKa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7AFABC433C7; Sat, 30 Dec 2023 12:05:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1703937937; bh=P0g5AUWOSOlDDOTnIXkV6nJwZBx6DPnXSQlRh18+Dgw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ObgGSyKaD/KBvGfwwgrlyM5yO3KAnfYxEKwQKG2VJnJoOnpK3XhltuWgaGbHKo9Tv IR2dEQF4Fjig8YWDQak+wEnbUzM1CGG4nNiI3sQQvG4CG1SSeXrHpmYBVAlfwNhnd3 I4kO2DxfIAUpm+q9CTHZ0ri47gpMcQqXOqxw/WAg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, kernel test robot , Arnd Bergmann , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , Paolo Abeni Subject: [PATCH 6.6 121/156] net: avoid build bug in skb extension length calculation Date: Sat, 30 Dec 2023 11:59:35 +0000 Message-ID: <20231230115816.316972376@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231230115812.333117904@linuxfoundation.org> References: <20231230115812.333117904@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Weißschuh commit d6e5794b06c0fab74fe6e4fa55d508a5ceb14735 upstream. GCC seems to incorrectly fail to evaluate skb_ext_total_length() at compile time under certain conditions. The issue even occurs if all values in skb_ext_type_len[] are "0", ruling out the possibility of an actual overflow. As the patch has been in mainline since v6.6 without triggering the problem it seems to be a very uncommon occurrence. As the issue only occurs when -fno-tree-loop-im is specified as part of CFLAGS_GCOV, disable the BUILD_BUG_ON() only when building with coverage reporting enabled. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202312171924.4FozI5FG-lkp@intel.com/ Suggested-by: Arnd Bergmann Link: https://lore.kernel.org/lkml/487cfd35-fe68-416f-9bfd-6bb417f98304@app.fastmail.com/ Fixes: 5d21d0a65b57 ("net: generalize calculation of skb extensions length") Cc: Signed-off-by: Thomas Weißschuh Acked-by: Arnd Bergmann Link: https://lore.kernel.org/r/20231218-net-skbuff-build-bug-v1-1-eefc2fb0a7d3@weissschuh.net Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman --- net/core/skbuff.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4810,7 +4810,9 @@ static __always_inline unsigned int skb_ static void skb_extensions_init(void) { BUILD_BUG_ON(SKB_EXT_NUM >= 8); +#if !IS_ENABLED(CONFIG_KCOV_INSTRUMENT_ALL) BUILD_BUG_ON(skb_ext_total_length() > 255); +#endif skbuff_ext_cache = kmem_cache_create("skbuff_ext_cache", SKB_EXT_ALIGN_VALUE * skb_ext_total_length(),