From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELtav7Tk/vFtSzaRxSNmnofX/Bjte4XjyyDjF+Dqcmy1yFZzAxoXTbtfRnqPUKWY3fYSDpOY ARC-Seal: i=1; a=rsa-sha256; t=1520970657; cv=none; d=google.com; s=arc-20160816; b=PDVcMzYWvAzgDS3v9v+SwQFl8xEQ9UgIklG2QI0+VV/jDWFhHn1/y3K0L500j2EFXy tPD5w1/mZr8DgoK0MPLNYC8nxUzmTfPyGriVbdsnp3Oscq1AZoVd5wIOj6KQbpV0vz61 bKvAGZiflszHbE/4otsGdzykMip4s9lh9QCqUJrVVzUiOmdj8yDBY43FykqLAQ6WMipJ 8nEeCvezsVN+w0JhdSOe8Uz7jiMHSQtNnsNiuWL82tvlKzOZajq3nivSxVxshTaBw+kR 3P8Af1vd0FyWpTgByDYswzxfqIPBLe29PG+K+ZjS+MP7xGVOc3p2nFUhNxCpHStCUqRr ImEw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=message-id:date:subject:cc:to:from:dkim-signature:delivered-to :list-id:list-subscribe:list-unsubscribe:list-help:list-post :precedence:mailing-list:arc-authentication-results; bh=z3LpzP0/rt/gJXoQPm132osZo5pA7pNwvqGehVEpDeI=; b=QK44QTP0L3+kRm4nY4m90tLLdrBuZeemjqBoZ6TwHOtNMs/0+hBVWiUeG1Xs88VUqY j/xCJzocoZPf2RuxOgQbUsV+9NqUBPKP5jWdJVt82XL9rXIvqI2RYzG3wfhEXjWjyezw Ru7oNuiM70usvDLj8UOKWLf6OlTwioAat76b2zytnP9cWR0kx4R0CM1L70qNKaUSMoCA +FHOSFJJQeopYgxTh34MuAgT8TRNN1VuWyWrmyFGwfJP69hHWnX39XFd7Q7ETQu5ATIN 81x4QOc7NVpg4euMpKBWUXcX1YpTvZds/WuyJ2m9FQ0VA7K1uPGknfM2sqf30u8LWM4N 4spQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=RrfBxtQd; spf=pass (google.com: domain of kernel-hardening-return-12514-gregkh=linuxfoundation.org@lists.openwall.com designates 195.42.179.200 as permitted sender) smtp.mailfrom=kernel-hardening-return-12514-gregkh=linuxfoundation.org@lists.openwall.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=RrfBxtQd; spf=pass (google.com: domain of kernel-hardening-return-12514-gregkh=linuxfoundation.org@lists.openwall.com designates 195.42.179.200 as permitted sender) smtp.mailfrom=kernel-hardening-return-12514-gregkh=linuxfoundation.org@lists.openwall.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm List-Post: List-Help: List-Unsubscribe: List-Subscribe: From: Salvatore Mesoraca To: linux-kernel@vger.kernel.org Cc: kernel-hardening@lists.openwall.com, linux-btrfs@vger.kernel.org, Chris Mason , David Sterba , Josef Bacik , Kees Cook , Salvatore Mesoraca Subject: [PATCH] Btrfs: drop a VLA in btrfs_check_super_csum() Date: Tue, 13 Mar 2018 20:50:22 +0100 Message-Id: <1520970622-19535-1-git-send-email-s.mesoraca16@gmail.com> X-Mailer: git-send-email 1.9.1 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594853328339341486?= X-GMAIL-MSGID: =?utf-8?q?1594853328339341486?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Avoid a VLA[1] by using a real constant expression instead of a variable. The compiler should be able to optimize the original code and avoid using an actual VLA. Anyway this change is useful because it will avoid a false positive with -Wvla, it might also help the compiler generating better code. [1] https://lkml.org/lkml/2018/3/7/621 Signed-off-by: Salvatore Mesoraca --- fs/btrfs/disk-io.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 21f34ad..88cef92 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -403,8 +403,7 @@ static int btrfs_check_super_csum(struct btrfs_fs_info *fs_info, if (csum_type == BTRFS_CSUM_TYPE_CRC32) { u32 crc = ~(u32)0; - const int csum_size = sizeof(crc); - char result[csum_size]; + char result[sizeof(crc)]; /* * The super_block structure does not span the whole @@ -415,7 +414,7 @@ static int btrfs_check_super_csum(struct btrfs_fs_info *fs_info, crc, BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE); btrfs_csum_final(crc, result); - if (memcmp(raw_disk_sb, result, csum_size)) + if (memcmp(raw_disk_sb, result, sizeof(result))) ret = 1; } -- 1.9.1