gcc-10: avoid shadowing standard library 'free()' in crypto

commit 1a263ae60b04de959d9ce9caea4889385eefcc7b upstream.

gcc-10 has started warning about conflicting types for a few new
built-in functions, particularly 'free()'.

This results in warnings like:

   crypto/xts.c:325:13: warning: conflicting types for built-in function ‘free’; expected ‘void(void *)’ [-Wbuiltin-declaration-mismatch]

because the crypto layer had its local freeing functions called
'free()'.

Gcc-10 is in the wrong here, since that function is marked 'static', and
thus there is no chance of confusion with any standard library function
namespace.

But the simplest thing to do is to just use a different name here, and
avoid this gcc mis-feature.

[ Side note: gcc knowing about 'free()' is in itself not the
  mis-feature: the semantics of 'free()' are special enough that a
  compiler can validly do special things when seeing it.

  So the mis-feature here is that gcc thinks that 'free()' is some
  restricted name, and you can't shadow it as a local static function.

  Making the special 'free()' semantics be a function attribute rather
  than tied to the name would be the much better model ]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/crypto/lrw.c b/crypto/lrw.c
index 5504d1325a56ab58d583724be58baef24d72b0bb..d55c9ee18817cba3c9ad7ebf190b9ec224ac4a80 100644 (file)
--- a/crypto/lrw.c
+++ b/crypto/lrw.c
@@ -453,7 +453,7 @@ static void exit_tfm(struct crypto_skcipher *tfm)
        crypto_free_skcipher(ctx->child);
 }
 
-static void free(struct skcipher_instance *inst)
+static void free_inst(struct skcipher_instance *inst)
 {
        crypto_drop_skcipher(skcipher_instance_ctx(inst));
        kfree(inst);
@@ -565,7 +565,7 @@ static int create(struct crypto_template *tmpl, struct rtattr **tb)
        inst->alg.encrypt = encrypt;
        inst->alg.decrypt = decrypt;
 
-       inst->free = free;
+       inst->free = free_inst;
 
        err = skcipher_register_instance(tmpl, inst);
        if (err)

diff --git a/crypto/xts.c b/crypto/xts.c
index ccf55fbb8bc2d6b7b889950215b14b3b77cff39e..5542dd10aedf264ab2c37a2e00341c2109b9a874 100644 (file)
--- a/crypto/xts.c
+++ b/crypto/xts.c
@@ -393,7 +393,7 @@ static void exit_tfm(struct crypto_skcipher *tfm)
        crypto_free_cipher(ctx->tweak);
 }
 
-static void free(struct skcipher_instance *inst)
+static void free_inst(struct skcipher_instance *inst)
 {
        crypto_drop_skcipher(skcipher_instance_ctx(inst));
        kfree(inst);
@@ -504,7 +504,7 @@ static int create(struct crypto_template *tmpl, struct rtattr **tb)
        inst->alg.encrypt = encrypt;
        inst->alg.decrypt = decrypt;
 
-       inst->free = free;
+       inst->free = free_inst;
 
        err = skcipher_register_instance(tmpl, inst);
        if (err)