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 886f91f2426c6483bc37482d42b7fa9da44cb2bb..1b73fec817cf7b206f9122c50ceb1b8695d468b1 100644 (file)
--- a/crypto/lrw.c
+++ b/crypto/lrw.c
@@ -531,7 +531,7 @@ 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);
@@ -642,7 +642,7 @@ 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 e31828ed00466cc08e8ee2e73bacb2d99c1e0a34..f5fba941d6f6c0d8df348f632fbc4e8eeb6eb63a 100644 (file)
--- a/crypto/xts.c
+++ b/crypto/xts.c
@@ -469,7 +469,7 @@ 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);
@@ -580,7 +580,7 @@ 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)