Re: [PATCH v12 1/4] pstore/blk: new support logger for block devices

[Dan Carpenter]

Hi liaoweixiong,

url:    https://github.com/0day-ci/linux/commits/liaoweixiong/pstore-block-new-support-logger-for-block-devices/20190303-142003
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/pstore

smatch warnings:
fs/pstore/blkzone.c:180 blkz_zone_write() error: we previously assumed 'zone->buffer' could be null (see line 167)

# https://github.com/0day-ci/linux/commit/113727d0f1946ad094dbc6531d653a88c7a221bf
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 113727d0f1946ad094dbc6531d653a88c7a221bf
vim +180 fs/pstore/blkzone.c

113727d0 liaoweixiong 2019-02-28  153  
113727d0 liaoweixiong 2019-02-28  154  static int blkz_zone_write(struct blkz_zone *zone,
113727d0 liaoweixiong 2019-02-28  155  		enum blkz_flush_mode flush_mode, const char *buf,
113727d0 liaoweixiong 2019-02-28  156  		size_t len, unsigned long off)
113727d0 liaoweixiong 2019-02-28  157  {
113727d0 liaoweixiong 2019-02-28  158  	struct blkz_info *info = blkz_cxt.bzinfo;
113727d0 liaoweixiong 2019-02-28  159  	ssize_t wcnt;
113727d0 liaoweixiong 2019-02-28  160  	ssize_t (*writeop)(const char *buf, size_t bytes, loff_t pos);
113727d0 liaoweixiong 2019-02-28  161  	size_t wlen;
113727d0 liaoweixiong 2019-02-28  162  
113727d0 liaoweixiong 2019-02-28  163  	if (off > zone->buffer_size)
113727d0 liaoweixiong 2019-02-28  164  		return -EINVAL;
113727d0 liaoweixiong 2019-02-28  165  	wlen = min_t(size_t, len, zone->buffer_size - off);
113727d0 liaoweixiong 2019-02-28  166  	if (flush_mode != FLUSH_META && flush_mode != FLUSH_NONE) {
113727d0 liaoweixiong 2019-02-28 @167  		if (buf && zone->buffer)
                                                           ^^^^^^^^^^^^
Check.

113727d0 liaoweixiong 2019-02-28  168  			memcpy(zone->buffer->data + off, buf, wlen);
113727d0 liaoweixiong 2019-02-28  169  		atomic_set(&zone->buffer->datalen, wlen + off);
113727d0 liaoweixiong 2019-02-28  170  	}
113727d0 liaoweixiong 2019-02-28  171  
113727d0 liaoweixiong 2019-02-28  172  	writeop = is_on_panic() ? info->panic_write : info->write;
113727d0 liaoweixiong 2019-02-28  173  	if (!writeop)
113727d0 liaoweixiong 2019-02-28  174  		return -EINVAL;
113727d0 liaoweixiong 2019-02-28  175  
113727d0 liaoweixiong 2019-02-28  176  	switch (flush_mode) {
113727d0 liaoweixiong 2019-02-28  177  	case FLUSH_NONE:
113727d0 liaoweixiong 2019-02-28  178  		return 0;
113727d0 liaoweixiong 2019-02-28  179  	case FLUSH_PART:
113727d0 liaoweixiong 2019-02-28 @180  		wcnt = writeop((const char *)zone->buffer->data + off, wlen,
                                                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Unchecked.

113727d0 liaoweixiong 2019-02-28  181  				zone->off + sizeof(*zone->buffer) + off);
                                                                                    ^^^^^^^^^^^^
This is weird.  I can't fetch for-next/pstore so I don't know what
type "buffer" is.  It's vague.  We also have ->buffer_size which seems
like a more expected way to describe the size.

113727d0 liaoweixiong 2019-02-28  182  		if (wcnt != wlen)
113727d0 liaoweixiong 2019-02-28  183  			goto set_dirty;
113727d0 liaoweixiong 2019-02-28  184  	case FLUSH_META:
113727d0 liaoweixiong 2019-02-28  185  		wlen = sizeof(struct blkz_buffer);
113727d0 liaoweixiong 2019-02-28  186  		wcnt = writeop((const char *)zone->buffer, wlen, zone->off);
113727d0 liaoweixiong 2019-02-28  187  		if (wcnt != wlen)
113727d0 liaoweixiong 2019-02-28  188  			goto set_dirty;
113727d0 liaoweixiong 2019-02-28  189  		break;
113727d0 liaoweixiong 2019-02-28  190  	case FLUSH_ALL:
113727d0 liaoweixiong 2019-02-28  191  		wlen = buffer_datalen(zone) + sizeof(*zone->buffer);
113727d0 liaoweixiong 2019-02-28  192  		wcnt = writeop((const char *)zone->buffer, wlen, zone->off);
113727d0 liaoweixiong 2019-02-28  193  		if (wcnt != wlen)
113727d0 liaoweixiong 2019-02-28  194  			goto set_dirty;
113727d0 liaoweixiong 2019-02-28  195  		break;
113727d0 liaoweixiong 2019-02-28  196  	}
113727d0 liaoweixiong 2019-02-28  197  
113727d0 liaoweixiong 2019-02-28  198  	return 0;
113727d0 liaoweixiong 2019-02-28  199  set_dirty:
113727d0 liaoweixiong 2019-02-28  200  	pr_err("write failed with %zd returned, set dirty\n", wcnt);
113727d0 liaoweixiong 2019-02-28  201  	atomic_set(&zone->dirty, true);
113727d0 liaoweixiong 2019-02-28  202  	return -EBUSY;
113727d0 liaoweixiong 2019-02-28  203  }
113727d0 liaoweixiong 2019-02-28  204  

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