[PATCH v2 1/3] crypto/luks: Initialize stack variable to silence warning

[Daniel Xu]

With `../configure --enable-sanitizers`, I was getting the following
build error:

        In file included from /usr/include/string.h:535,
                         from /home/dxu/dev/qemu/include/qemu/osdep.h:99,
                         from ../crypto/block-luks.c:21:
        In function ‘memset’,
            inlined from ‘qcrypto_block_luks_store_key’ at 
../crypto/block-luks.c:843:9:
        /usr/include/bits/string_fortified.h:59:10: error: ‘splitkeylen’ may be 
used
        uninitialized [-Werror=maybe-uninitialized]
           59 |   return __builtin___memset_chk (__dest, __ch, __len,
              |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           60 |                                  __glibc_objsize0 (__dest));
              |                                  ~~~~~~~~~~~~~~~~~~~~~~~~~~
        ../crypto/block-luks.c: In function ‘qcrypto_block_luks_store_key’:
        ../crypto/block-luks.c:699:12: note: ‘splitkeylen’ was declared here
          699 |     size_t splitkeylen;
              |            ^~~~~~~~~~~
        cc1: all warnings being treated as errors

The function is actually correct -- in the cleanup branch `splitkeylen`
usage is guarded by checking `splitkey` nullness. But the compiler is
not smart enough to realize that.

Fix warning by initializing the variable.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
---
 crypto/block-luks.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crypto/block-luks.c b/crypto/block-luks.c
index 5688783ab1..bfdef25c80 100644
--- a/crypto/block-luks.c
+++ b/crypto/block-luks.c
@@ -696,7 +696,7 @@ qcrypto_block_luks_store_key(QCryptoBlock *block,
     QCryptoBlockLUKS *luks = block->opaque;
     QCryptoBlockLUKSKeySlot *slot;
     g_autofree uint8_t *splitkey = NULL;
-    size_t splitkeylen;
+    size_t splitkeylen = 0;
     g_autofree uint8_t *slotkey = NULL;
     g_autoptr(QCryptoCipher) cipher = NULL;
     g_autoptr(QCryptoIVGen) ivgen = NULL;
-- 
2.39.1