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[67.216.221.250]) by smtp.gmail.com with ESMTPSA id v79sm8596712pfc.197.2020.10.26.07.43.22 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 26 Oct 2020 07:43:22 -0700 (PDT) From: xiakaixu1987@gmail.com X-Google-Original-From: kaixuxia@tencent.com To: linux-ext4@vger.kernel.org Cc: tytso@mit.edu, adilger.kernel@dilger.ca, Kaixu Xia Subject: [PATCH] ext4: do the quotafile name safe check before allocating new string Date: Mon, 26 Oct 2020 22:43:17 +0800 Message-Id: <1603723397-14344-1-git-send-email-kaixuxia@tencent.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org From: Kaixu Xia Now we do the quotafile name safe check after allocating the new string by using kmalloc(), and have to release the string with kfree() if check fails. Maybe we can check them before allocating memory and directly return error if check fails to avoid the unnecessary kmalloc()/kfree() operations. Signed-off-by: Kaixu Xia --- fs/ext4/super.c | 29 +++++++++++++---------------- 1 file changed, 13 insertions(+), 16 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 5308f0d5fb5a..83fdde498414 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1861,7 +1861,6 @@ static int set_qf_name(struct super_block *sb, int qtype, substring_t *args) { struct ext4_sb_info *sbi = EXT4_SB(sb); char *qname, *old_qname = get_qf_name(sb, sbi, qtype); - int ret = -1; if (sb_any_quota_loaded(sb) && !old_qname) { ext4_msg(sb, KERN_ERR, @@ -1874,32 +1873,30 @@ static int set_qf_name(struct super_block *sb, int qtype, substring_t *args) "ignored when QUOTA feature is enabled"); return 1; } - qname = match_strdup(args); - if (!qname) { - ext4_msg(sb, KERN_ERR, - "Not enough memory for storing quotafile name"); - return -1; - } if (old_qname) { - if (strcmp(old_qname, qname) == 0) - ret = 1; - else + if (strlen(old_qname) != args->to - args->from || + strncmp(old_qname, args->from, args->to - args->from)) { ext4_msg(sb, KERN_ERR, "%s quota file already specified", QTYPE2NAME(qtype)); - goto errout; + return -1; + } + return 1; } - if (strchr(qname, '/')) { + if (strnchr(args->from, args->to - args->from, '/')) { ext4_msg(sb, KERN_ERR, "quotafile must be on filesystem root"); - goto errout; + return -1; + } + qname = match_strdup(args); + if (!qname) { + ext4_msg(sb, KERN_ERR, + "Not enough memory for storing quotafile name"); + return -1; } rcu_assign_pointer(sbi->s_qf_names[qtype], qname); set_opt(sb, QUOTA); return 1; -errout: - kfree(qname); - return ret; } static int clear_qf_name(struct super_block *sb, int qtype)