| Message ID | Y5hXUlvSmHrP8PTN@gondor.apana.org.au (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | crypto: arm/sha1 - Fix clang function cast warnings | expand |
On Tue, 13 Dec 2022 at 11:43, Herbert Xu <herbert@gondor.apana.org.au> wrote: > > On Thu, Dec 08, 2022 at 07:05:45PM +0100, Ard Biesheuvel wrote: > > > > We can, as the BUILD_BUG() will catch it if struct sha1_state gets > > modified in an incompatible way. > > Thanks for confirming! > > ---8<--- > Instead of casting the function which upsets clang for some reason, > change the assembly function siganture instead. > > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> > > diff --git a/arch/arm/crypto/sha1_glue.c b/arch/arm/crypto/sha1_glue.c > index 6c2b849e459d..95a727bcd664 100644 > --- a/arch/arm/crypto/sha1_glue.c > +++ b/arch/arm/crypto/sha1_glue.c > @@ -21,31 +21,29 @@ > > #include "sha1.h" > > -asmlinkage void sha1_block_data_order(u32 *digest, > - const unsigned char *data, unsigned int rounds); > +asmlinkage void sha1_block_data_order(struct sha1_state *digest, > + const u8 *data, int rounds); > > int sha1_update_arm(struct shash_desc *desc, const u8 *data, > unsigned int len) > { > - /* make sure casting to sha1_block_fn() is safe */ > + /* make sure signature matches sha1_block_fn() */ > BUILD_BUG_ON(offsetof(struct sha1_state, state) != 0); > > - return sha1_base_do_update(desc, data, len, > - (sha1_block_fn *)sha1_block_data_order); > + return sha1_base_do_update(desc, data, len, sha1_block_data_order); > } > EXPORT_SYMBOL_GPL(sha1_update_arm); > > static int sha1_final(struct shash_desc *desc, u8 *out) > { > - sha1_base_do_finalize(desc, (sha1_block_fn *)sha1_block_data_order); > + sha1_base_do_finalize(desc, sha1_block_data_order); > return sha1_base_finish(desc, out); > } > > int sha1_finup_arm(struct shash_desc *desc, const u8 *data, > unsigned int len, u8 *out) > { > - sha1_base_do_update(desc, data, len, > - (sha1_block_fn *)sha1_block_data_order); > + sha1_base_do_update(desc, data, len, sha1_block_data_order); > return sha1_final(desc, out); > } > EXPORT_SYMBOL_GPL(sha1_finup_arm); > -- > Email: Herbert Xu <herbert@gondor.apana.org.au> > Home Page: http://gondor.apana.org.au/~herbert/ > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
> On Thu, Dec 08, 2022 at 07:05:45PM +0100, Ard Biesheuvel wrote: ... > Instead of casting the function which upsets clang for some reason, > change the assembly function siganture instead. Since the assembly function is passed directly to the generic sha1 helper (sha1_base_do_update) then I agree that is the right approach. The casts are a clue that something is not quite right. There are several other arm modules with casts, not just sha1: sha1, sha1_neon, sha256, sha256_neon, sha2-ce, sha512, sha512-neon > - /* make sure casting to sha1_block_fn() is safe */ > + /* make sure signature matches sha1_block_fn() */ > BUILD_BUG_ON(offsetof(struct sha1_state, state) != 0); I think this wording used by some of the modules provides a better explanation (e.g. arch/arm/sha512-neon-glue.c): * Make sure struct sha512_state begins directly with the SHA512 * 512-bit internal state, as this is what the asm functions expect. Most of them only access the first field in the structure, so I'd be tempted to change the callers to pass the offset of the state subfield and make the prototypes match that, changing: block_fn(sctx, data, blocks); to block_fn(sctx->state, data, blocks); However, a few of them (e.g., arm64 sha1_neon_ce) do carefully manipulate the other fields (it's important to not confuse the caller by doing so), so that's not viable for sha1.
On Tue, Dec 13, 2022 at 06:43:30PM +0800, Herbert Xu wrote: > -asmlinkage void sha1_block_data_order(u32 *digest, > - const unsigned char *data, unsigned int rounds); > +asmlinkage void sha1_block_data_order(struct sha1_state *digest, > + const u8 *data, int rounds); The last parameter should be called 'blocks', not 'rounds'. > int sha1_update_arm(struct shash_desc *desc, const u8 *data, > unsigned int len) > { > - /* make sure casting to sha1_block_fn() is safe */ > + /* make sure signature matches sha1_block_fn() */ > BUILD_BUG_ON(offsetof(struct sha1_state, state) != 0); The above comment doesn't really make sense, since making sure function signatures match is the responsibility of the compiler. A better comment would be: /* sha1_block_data_order() expects the actual state at the beginning. */ It would also be helpful to add a comment to the definition of struct sha1_state, analogous to the comment in struct blake2s_state: struct sha1_state { /* 'state' is used by assembly code, so keep it as-is. */ u32 state[SHA1_DIGEST_SIZE / 4]; - Eric
diff --git a/arch/arm/crypto/sha1_glue.c b/arch/arm/crypto/sha1_glue.c index 6c2b849e459d..95a727bcd664 100644 --- a/arch/arm/crypto/sha1_glue.c +++ b/arch/arm/crypto/sha1_glue.c @@ -21,31 +21,29 @@ #include "sha1.h" -asmlinkage void sha1_block_data_order(u32 *digest, - const unsigned char *data, unsigned int rounds); +asmlinkage void sha1_block_data_order(struct sha1_state *digest, + const u8 *data, int rounds); int sha1_update_arm(struct shash_desc *desc, const u8 *data, unsigned int len) { - /* make sure casting to sha1_block_fn() is safe */ + /* make sure signature matches sha1_block_fn() */ BUILD_BUG_ON(offsetof(struct sha1_state, state) != 0); - return sha1_base_do_update(desc, data, len, - (sha1_block_fn *)sha1_block_data_order); + return sha1_base_do_update(desc, data, len, sha1_block_data_order); } EXPORT_SYMBOL_GPL(sha1_update_arm); static int sha1_final(struct shash_desc *desc, u8 *out) { - sha1_base_do_finalize(desc, (sha1_block_fn *)sha1_block_data_order); + sha1_base_do_finalize(desc, sha1_block_data_order); return sha1_base_finish(desc, out); } int sha1_finup_arm(struct shash_desc *desc, const u8 *data, unsigned int len, u8 *out) { - sha1_base_do_update(desc, data, len, - (sha1_block_fn *)sha1_block_data_order); + sha1_base_do_update(desc, data, len, sha1_block_data_order); return sha1_final(desc, out); } EXPORT_SYMBOL_GPL(sha1_finup_arm);