Messages in this thread | | | Subject | Re: [PATCH 11/11] crypto: skcipher: Remove VLA usage for SKCIPHER_REQUEST_ON_STACK | From | Christophe Leroy <> | Date | Wed, 20 Jun 2018 20:22:34 +0000 |
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On 06/20/2018 07:04 PM, Kees Cook wrote: > In the quest to remove all stack VLA usage from the kernel[1], this > caps the skcipher request size similar to other limits and adds a sanity > check at registration. > > [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com > > Signed-off-by: Kees Cook <keescook@chromium.org>
crypto/echainiv.c: In function ‘echainiv_encrypt’: crypto/echainiv.c:88:1: warning: the frame size of 2120 bytes is larger than 1024 bytes [-Wframe-larger-than=] crypto/authenc.c: In function ‘crypto_authenc_copy_assoc’: crypto/authenc.c:197:1: warning: the frame size of 2120 bytes is larger than 1024 bytes [-Wframe-larger-than=] crypto/authencesn.c: In function ‘crypto_authenc_esn_copy’: crypto/authencesn.c:194:1: warning: the frame size of 2120 bytes is larger than 1024 bytes [-Wframe-larger-than=] crypto/algif_aead.c: In function ‘crypto_aead_copy_sgl’: crypto/algif_aead.c:90:1: warning: the frame size of 2120 bytes is larger than 1024 bytes [-Wframe-larger-than=]
Christophe
> --- > include/crypto/internal/skcipher.h | 1 + > include/crypto/skcipher.h | 4 +++- > 2 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/include/crypto/internal/skcipher.h b/include/crypto/internal/skcipher.h > index e42f7063f245..5035482cbe68 100644 > --- a/include/crypto/internal/skcipher.h > +++ b/include/crypto/internal/skcipher.h > @@ -130,6 +130,7 @@ static inline struct crypto_skcipher *crypto_spawn_skcipher( > static inline void crypto_skcipher_set_reqsize( > struct crypto_skcipher *skcipher, unsigned int reqsize) > { > + BUG_ON(reqsize > SKCIPHER_MAX_REQSIZE); > skcipher->reqsize = reqsize; > } > > diff --git a/include/crypto/skcipher.h b/include/crypto/skcipher.h > index 2f327f090c3e..25294d0089b2 100644 > --- a/include/crypto/skcipher.h > +++ b/include/crypto/skcipher.h > @@ -139,9 +139,11 @@ struct skcipher_alg { > struct crypto_alg base; > }; > > +#define SKCIPHER_MAX_REQSIZE (PAGE_SIZE / 8) > + > #define SKCIPHER_REQUEST_ON_STACK(name, tfm) \ > char __##name##_desc[sizeof(struct skcipher_request) + \ > - crypto_skcipher_reqsize(tfm)] CRYPTO_MINALIGN_ATTR; \ > + SKCIPHER_MAX_REQSIZE] CRYPTO_MINALIGN_ATTR; \ > struct skcipher_request *name = (void *)__##name##_desc > > /** >
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