Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 10 Jul 2023 12:56:30 +0300
From:   Dan Carpenter <dan.carpenter@linaro.org>
To:     Linke Li <lilinke99@foxmail.com>
Cc:     linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jan Kara <jack@suse.cz>, Linke Li <lilinke99@gmail.com>
Subject: Re: [PATCH] isofs: fix undefined behavior in iso_date()
Message-ID: <79582844-3178-451c-822e-a692bfd27e9c@moroto.mountain>
References: <tencent_4D921A8D1F69E70C85C28875DC829E28EC09@qq.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <tencent_4D921A8D1F69E70C85C28875DC829E28EC09@qq.com>
Precedence: bulk

It looks like maybe there is an issue with "year" as well.

fs/isofs/util.c
    19  int iso_date(u8 *p, int flag)
    20  {
    21          int year, month, day, hour, minute, second, tz;
    22          int crtime;
    23
    24          year = p[0];
                       ^^^^^
year is 0-255.

    25          month = p[1];
    26          day = p[2];
    27          hour = p[3];
    28          minute = p[4];
    29          second = p[5];
    30          if (flag == 0) tz = p[6]; /* High sierra has no time zone */
    31          else tz = 0;
    32          
    33          if (year < 0) {
                    ^^^^^^^^
But this checks year for < 0 which is impossible.  Should it be:

	year = (signed char)p[0];?

    34                  crtime = 0;
    35          } else {
    36                  crtime = mktime64(year+1900, month, day, hour, minute, second);
    37
    38                  /* sign extend */
    39                  if (tz & 0x80)
    40                          tz |= (-1 << 8);
    41                  
    42                  /*

regards,
dan carpenter