On Mon, Mar 13 2017 at 10:19am -0400,
Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> Hello Milan Broz,
>
> This is a semi-automatic email about new static checker warnings.
>
> The patch 858516b7881e: "dm crypt: add cryptographic data integrity
> protection (authenticated encryption)" from Jan 4, 2017, leads to the
> following Smatch complaint:
>
> drivers/md/dm-crypt.c:1390 crypt_alloc_buffer()
> error: we previously assumed 'clone' could be null (see line 1362)
>
> drivers/md/dm-crypt.c
> 1361 clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
> 1362 if (!clone)
> ^^^^^^
> We can be NULL on this path.
>
> 1363 goto return_clone;
> 1364
> 1365 clone_init(io, clone);
> 1366
> 1367 remaining_size = size;
> 1368
> 1369 for (i = 0; i < nr_iovecs; i++) {
> 1370 page = mempool_alloc(cc->page_pool, gfp_mask);
> 1371 if (!page) {
> 1372 crypt_free_buffer_pages(cc, clone);
> 1373 bio_put(clone);
> 1374 gfp_mask |= __GFP_DIRECT_RECLAIM;
> 1375 goto retry;
> 1376 }
> 1377
> 1378 len = (remaining_size > PAGE_SIZE) ? PAGE_SIZE : remaining_size;
> 1379
> 1380 bio_add_page(clone, page, len, 0);
> 1381
> 1382 remaining_size -= len;
> 1383 }
> 1384
> 1385 return_clone:
> 1386 if (unlikely(gfp_mask & __GFP_DIRECT_RECLAIM))
> 1387 mutex_unlock(&cc->bio_alloc_lock);
> 1388
> 1389 /* Allocate space for integrity tags */
> 1390 if (dm_crypt_integrity_io_alloc(io, clone)) {
> ^^^^^
> Oops inside new function call.
>
> 1391 crypt_free_buffer_pages(cc, clone);
> 1392 bio_put(clone);
Thanks for the report. This code makes no sense as is.
Milan, please help me understand why you're allocating memory needed for
integrity tags in this 'return_clone' error path.
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