[ammarfaizi2-block:dhowells/linux-fs/netfs-maple 42/44] fs/afs/write.c:265:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true

[kernel test robot <lkp@intel.com>]

tree:   https://github.com/ammarfaizi2/linux-block dhowells/linux-fs/netfs-maple
head:   931e50676c6598d0eda1954ead465519ff91874d
commit: 0565641524458774e47a4d1fd06f80d0bd62965f [42/44] afs: [DON'T MERGE] Implement trivial content crypto for testing purposes
config: i386-randconfig-a015 (https://download.01.org/0day-ci/archive/20220423/202204231313.4Udoczm1-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 5bd87350a5ae429baf8f373cb226a57b62f87280)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/ammarfaizi2/linux-block/commit/0565641524458774e47a4d1fd06f80d0bd62965f
        git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
        git fetch --no-tags ammarfaizi2-block dhowells/linux-fs/netfs-maple
        git checkout 0565641524458774e47a4d1fd06f80d0bd62965f
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash fs/afs/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> fs/afs/write.c:265:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
           if (!buf)
               ^~~~
   fs/afs/write.c:335:9: note: uninitialized use occurs here
           return ret;
                  ^~~
   fs/afs/write.c:265:2: note: remove the 'if' if its condition is always false
           if (!buf)
           ^~~~~~~~~
   fs/afs/write.c:247:9: note: initialize the variable 'ret' to silence this warning
           int ret;
                  ^
                   = 0
   fs/afs/write.c:372:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
           if (!buf)
               ^~~~
   fs/afs/write.c:442:9: note: uninitialized use occurs here
           return ret;
                  ^~~
   fs/afs/write.c:372:2: note: remove the 'if' if its condition is always false
           if (!buf)
           ^~~~~~~~~
   fs/afs/write.c:354:9: note: initialize the variable 'ret' to silence this warning
           int ret;
                  ^
                   = 0
   2 warnings generated.


vim +265 fs/afs/write.c

   230	
   231	/*
   232	 * Encrypt part of a write for fscrypt.  The caller reserved an extra
   233	 * scatterlist element before each of source_sg and dest_sg for our purposes,
   234	 * should we need them.
   235	 */
   236	int afs_encrypt_block(struct netfs_io_request *wreq, loff_t pos, size_t len,
   237			      struct scatterlist *source_sg, unsigned int n_source,
   238			      struct scatterlist *dest_sg, unsigned int n_dest)
   239	{
   240		struct crypto_sync_skcipher *ci;
   241		struct skcipher_request *req;
   242		struct crypto_skcipher *tfm;
   243		struct sha256_state *sha;
   244		void *buf = NULL;
   245		__be64 *session_key;
   246		u8 *iv, *b0;
   247		int ret;
   248	
   249		ci = crypto_alloc_sync_skcipher("cts(cbc(aes))", 0, 0);
   250		if (IS_ERR(ci)) {
   251			ret = PTR_ERR(ci);
   252			pr_err("Can't allocate cipher: %d\n", ret);
   253			goto error;
   254		}
   255		tfm = &ci->base;
   256	
   257		if (crypto_sync_skcipher_ivsize(ci) > 16 &&
   258		    crypto_sync_skcipher_blocksize(ci) > 16) {
   259			pr_err("iv wrong size: %u\n", crypto_sync_skcipher_ivsize(ci));
   260			ret = -EINVAL;
   261			goto error_ci;
   262		}
   263	
   264		buf = kzalloc(4 * 16 + sizeof(*sha), GFP_KERNEL);
 > 265		if (!buf)
   266			goto error_ci;
   267		b0 = buf;
   268		iv = buf + 32;
   269		session_key = buf + 48;
   270		session_key[0] = cpu_to_be64(pos);
   271		session_key[1] = cpu_to_le64(pos);
   272		sha = buf + 64;
   273	
   274		*(__be64 *)iv = pos;
   275	
   276		ret = crypto_sync_skcipher_setkey(ci, (u8 *)session_key, 16);
   277		if (ret < 0) {
   278			pr_err("Setkey failed: %d\n", ret);
   279			goto error_ci;
   280		}
   281	
   282		ret = -ENOMEM;
   283		req = skcipher_request_alloc(tfm, GFP_NOFS);
   284		if (!req)
   285			goto error_ci;
   286	
   287		skcipher_request_set_sync_tfm(req, ci);
   288		skcipher_request_set_callback(req, 0, NULL, NULL);
   289	
   290		/* If the length is so short that the CTS algorithm will refuse to
   291		 * handle it, prepend a predictable block on the front and discard the
   292		 * output.  Since CTS does draw data backwards, we can regenerate the
   293		 * encryption on just that block at decryption time.
   294		 */
   295		if (len < 16) {
   296			unsigned int i;
   297			u8 *p = buf + 16;
   298	
   299			kdebug("preblock %16phN", iv);
   300			sha256_init(sha);
   301			sha256_update(sha, iv, 32); /* iv and session key */
   302			sha256_final(sha, b0);
   303			kdebug("preblock %16phN", b0);
   304	
   305			netfs_dump_sg("SRC", source_sg, n_source);
   306			if (sg_copy_to_buffer(source_sg, n_source, p, len) != len) {
   307				ret = -EIO;
   308				goto error_req;
   309			}
   310	
   311			for (i = 0; i < len; i++)
   312				p[i] += b0[i];
   313	
   314			if (sg_copy_from_buffer(dest_sg, n_dest, p, len) != len) {
   315				ret = -EIO;
   316				goto error_req;
   317			}
   318			netfs_dump_sg("DST", dest_sg, n_dest);
   319			ret = 0;
   320		} else {
   321			netfs_dump_sg("SRC", source_sg, n_source);
   322			skcipher_request_set_crypt(req, source_sg, dest_sg, len, iv);
   323			ret = crypto_skcipher_encrypt(req);
   324			if (ret < 0)
   325				pr_err("Encrypt failed: %d\n", ret);
   326			netfs_dump_sg("DST", dest_sg, n_dest);
   327		}
   328	
   329	error_req:
   330		skcipher_request_free(req);
   331	error_ci:
   332		kfree(buf);
   333		crypto_free_sync_skcipher(ci);
   334	error:
   335		return ret;
   336	}
   337	

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