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([2404:7a87:83e0:f800:5c24:508b:d8c0:f3b]) by smtp.gmail.com with ESMTPSA id d13sm2385311pjz.3.2020.08.12.08.04.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 12 Aug 2020 08:04:54 -0700 (PDT) Subject: Re: [PATCH 1/2] exfat: add NameLength check when extracting name To: Namjae Jeon Cc: kohada.tetsuhiro@dc.mitsubishielectric.co.jp, mori.takahiro@ab.mitsubishielectric.co.jp, motai.hirotaka@aj.mitsubishielectric.co.jp, 'Sungjong Seo' , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <20200806055653.9329-1-kohada.t2@gmail.com> <003d01d66edd$5baf4810$130dd830$@samsung.com> From: Tetsuhiro Kohada Message-ID: Date: Thu, 13 Aug 2020 00:04:51 +0900 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <003d01d66edd$5baf4810$130dd830$@samsung.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thank you for your reply. >> -static void exfat_get_uniname_from_ext_entry(struct super_block *sb, >> - struct exfat_chain *p_dir, int entry, unsigned short *uniname) >> +static int exfat_get_uniname_from_name_entries(struct exfat_entry_set_cache *es, >> + struct exfat_uni_name *uniname) >> { >> - int i; >> - struct exfat_entry_set_cache *es; >> + int n, l, i; >> struct exfat_dentry *ep; >> >> - es = exfat_get_dentry_set(sb, p_dir, entry, ES_ALL_ENTRIES); >> - if (!es) >> - return; >> + uniname->name_len = es->de_stream->name_len; >> + if (uniname->name_len == 0) >> + return -EIO; > Can we validate ->name_len and name entry ->type in exfat_get_dentry_set() ? Yes. As I wrote in a previous email, entry type validation, name-length validation, and name extraction should not be separated, so implement all of these in exfat_get_dentry_set(). It can be easily implemented by adding uniname to exfat_entry_set_cache and calling exfat_get_uniname_from_name_entries() from exfat_get_dentry_set(). However, that would be over-implementation. Not all callers of exfat_get_dentry_set() need a name. It is enough to validate the name when it is needed. This is a file-system driver, not fsck. Validation is possible in exfat_get_dentry_set(), but unnecessary. Why do you want to validate the name in exfat_get_dentry_set()? BR --- Tetsuhiro Kohada