[PATCH 0/2] Removing the use of VLAIS from the Linux Kernel

STALE5094d

Revision v1 of 2 in this series.

6 messages, 4 authors, 2012-11-01 · open the first message on its own page

[PATCH 0/2] Removing the use of VLAIS from the Linux Kernel

From: Behan Webster <hidden>
Date: 2012-10-30 18:37:18 

The use of variable length arrays in structs (VLAIS) in the Linux Kernel code
precludes the use of compilers which don't implement VLAIS (for instance the
Clang compiler). The LLVMLinux Project is working towards the ability of
providing the Linux kernel developer the choice of using the Clang compiler
toolchain. This is a part of a series of patches which remove the use of VLAIS
from crypto code, dm-crypt, jbd2, libcrc32c, netfilter, and usb gadget. Other
patches to allow Clang to be used will follow.

Jan-Simon Möller (2):
  Remove VLAIS usage from crypto/hmac.c
  Remove VLAIS usage from crypto/testmgr.c

 crypto/hmac.c    |   27 +++++++++++++--------------
 crypto/testmgr.c |   23 +++++++++++++----------
 2 files changed, 26 insertions(+), 24 deletions(-)

-- 
1.7.9.5

[PATCH 2/2] Remove VLAIS usage from crypto/testmgr.c

From: Behan Webster <hidden>
Date: 2012-10-30 18:37:22 

From: Jan-Simon Möller <redacted>

The use of variable length arrays in structs (VLAIS) in the Linux Kernel code
precludes the use of compilers which don't implement VLAIS (for instance the
Clang compiler). This patch instead allocates the appropriate amount of memory
using an char array.

Patch from series at
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120507/142707.html
by PaX Team.

Signed-off-by: Jan-Simon Möller <redacted>
Cc: pageexec@freemail.hu
Signed-off-by: Behan Webster <redacted>
---
 crypto/testmgr.c |   23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index 941d75c..5b7b3a6 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c
@@ -1578,16 +1578,19 @@ static int alg_test_crc32c(const struct alg_test_desc *desc,
 	}
 
 	do {
-		struct {
-			struct shash_desc shash;
-			char ctx[crypto_shash_descsize(tfm)];
-		} sdesc;
-
-		sdesc.shash.tfm = tfm;
-		sdesc.shash.flags = 0;
-
-		*(u32 *)sdesc.ctx = le32_to_cpu(420553207);
-		err = crypto_shash_final(&sdesc.shash, (u8 *)&val);
+		char sdesc[sizeof(struct shash_desc)
+			+ crypto_shash_descsize(tfm)
+			+ CRYPTO_MINALIGN] CRYPTO_MINALIGN_ATTR;
+		struct shash_desc *shash = (struct shash_desc *)sdesc;
+		u32 *ctx = (u32 *)((unsigned long)(sdesc
+			+ sizeof(struct shash_desc) + CRYPTO_MINALIGN - 1)
+			& ~(CRYPTO_MINALIGN - 1));
+
+		shash->tfm = tfm;
+		shash->flags = 0;
+
+		*ctx = le32_to_cpu(420553207);
+		err = crypto_shash_final(shash, (u8 *)&val);
 		if (err) {
 			printk(KERN_ERR "alg: crc32c: Operation failed for "
 			       "%s: %d\n", driver, err);
-- 
1.7.9.5

[PATCH 1/2] Remove VLAIS usage from crypto/hmac.c

From: Behan Webster <hidden>
Date: 2012-10-30 18:37:55 

From: Jan-Simon Möller <redacted>

The use of variable length arrays in structs (VLAIS) in the Linux Kernel code
precludes the use of compilers which don't implement VLAIS (for instance the
Clang compiler). This patch instead allocates the appropriate amount of memory
using an char array.

Patch from series at
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120507/142707.html
by PaX Team.

Signed-off-by: Jan-Simon Möller <redacted>
Cc: pageexec@freemail.hu
Signed-off-by: Behan Webster <redacted>
---
 crypto/hmac.c |   27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/crypto/hmac.c b/crypto/hmac.c
index 8d9544c..1061255 100644
--- a/crypto/hmac.c
+++ b/crypto/hmac.c
@@ -52,20 +52,19 @@ static int hmac_setkey(struct crypto_shash *parent,
 	struct hmac_ctx *ctx = align_ptr(opad + ss,
 					 crypto_tfm_ctx_alignment());
 	struct crypto_shash *hash = ctx->hash;
-	struct {
-		struct shash_desc shash;
-		char ctx[crypto_shash_descsize(hash)];
-	} desc;
+	char desc[sizeof(struct shash_desc) + crypto_shash_descsize(hash)
+		+ CRYPTO_MINALIGN] CRYPTO_MINALIGN_ATTR;
+	struct shash_desc *shash = (struct shash_desc *)desc;
 	unsigned int i;
 
-	desc.shash.tfm = hash;
-	desc.shash.flags = crypto_shash_get_flags(parent) &
-			    CRYPTO_TFM_REQ_MAY_SLEEP;
+	shash->tfm = hash;
+	shash->flags = crypto_shash_get_flags(parent)
+		& CRYPTO_TFM_REQ_MAY_SLEEP;
 
 	if (keylen > bs) {
 		int err;
 
-		err = crypto_shash_digest(&desc.shash, inkey, keylen, ipad);
+		err = crypto_shash_digest(shash, inkey, keylen, ipad);
 		if (err)
 			return err;
 
@@ -81,12 +80,12 @@ static int hmac_setkey(struct crypto_shash *parent,
 		opad[i] ^= 0x5c;
 	}
 
-	return crypto_shash_init(&desc.shash) ?:
-	       crypto_shash_update(&desc.shash, ipad, bs) ?:
-	       crypto_shash_export(&desc.shash, ipad) ?:
-	       crypto_shash_init(&desc.shash) ?:
-	       crypto_shash_update(&desc.shash, opad, bs) ?:
-	       crypto_shash_export(&desc.shash, opad);
+	return crypto_shash_init(shash) ?:
+	       crypto_shash_update(shash, ipad, bs) ?:
+	       crypto_shash_export(shash, ipad) ?:
+	       crypto_shash_init(shash) ?:
+	       crypto_shash_update(shash, opad, bs) ?:
+	       crypto_shash_export(shash, opad);
 }
 
 static int hmac_export(struct shash_desc *pdesc, void *out)
-- 
1.7.9.5

Re: [PATCH 2/2] Remove VLAIS usage from crypto/testmgr.c

From: Jussi Kivilinna <hidden>
Date: 2012-10-31 08:55:37 

Quoting Behan Webster [off-list ref]:
quoted hunk
From: Jan-Simon Möller <redacted>

The use of variable length arrays in structs (VLAIS) in the Linux Kernel code
precludes the use of compilers which don't implement VLAIS (for instance the
Clang compiler). This patch instead allocates the appropriate amount  
of memory
using an char array.

Patch from series at
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120507/142707.html
by PaX Team.

Signed-off-by: Jan-Simon Möller <redacted>
Cc: pageexec@freemail.hu
Signed-off-by: Behan Webster <redacted>
---
 crypto/testmgr.c |   23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index 941d75c..5b7b3a6 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c
@@ -1578,16 +1578,19 @@ static int alg_test_crc32c(const struct  
alg_test_desc *desc,
 	}

 	do {
-		struct {
-			struct shash_desc shash;
-			char ctx[crypto_shash_descsize(tfm)];
-		} sdesc;
-
-		sdesc.shash.tfm = tfm;
-		sdesc.shash.flags = 0;
-
-		*(u32 *)sdesc.ctx = le32_to_cpu(420553207);
-		err = crypto_shash_final(&sdesc.shash, (u8 *)&val);
+		char sdesc[sizeof(struct shash_desc)
+			+ crypto_shash_descsize(tfm)
+			+ CRYPTO_MINALIGN] CRYPTO_MINALIGN_ATTR;
+		struct shash_desc *shash = (struct shash_desc *)sdesc;
+		u32 *ctx = (u32 *)((unsigned long)(sdesc
+			+ sizeof(struct shash_desc) + CRYPTO_MINALIGN - 1)
+			& ~(CRYPTO_MINALIGN - 1));
I think you should use '(u32 *)shash_desc_ctx(shash)' instead of  
getting ctx pointer manually.
quoted hunk
+
+		shash->tfm = tfm;
+		shash->flags = 0;
+
+		*ctx = le32_to_cpu(420553207);
+		err = crypto_shash_final(shash, (u8 *)&val);
 		if (err) {
 			printk(KERN_ERR "alg: crc32c: Operation failed for "
 			       "%s: %d\n", driver, err);

Re: [PATCH 0/2] Removing the use of VLAIS from the Linux Kernel

From: David Miller <davem@davemloft.net>
Date: 2012-10-31 16:41:39 

I don't think imposing the limitations of a non-gcc compiler
is rasonable.

Re: [PATCH 0/2] Removing the use of VLAIS from the Linux Kernel

From: Herbert Xu <hidden>
Date: 2012-11-01 00:41:54 

On Wed, Oct 31, 2012 at 12:41:32PM -0400, David Miller wrote:
I don't think imposing the limitations of a non-gcc compiler
is rasonable.
I agree.
-- 
Email: Herbert Xu [off-list ref]
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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