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Message-ID: <20180427025728.GA38607@beast>
Date: Thu, 26 Apr 2018 19:57:28 -0700
From: Kees Cook <keescook@...omium.org>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Gilad Ben-Yossef <gilad@...yossef.com>,
linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] crypto: tcrypt: Remove VLA usage
In the quest to remove all stack VLA usage from the kernel[1], this
allocates the return code buffers before starting jiffie timers, rather
than using stack space for the array. Additionally cleans up some exit
paths and make sure that the num_mb module_param() is used only once
per execution to avoid possible races in the value changing.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Signed-off-by: Kees Cook <keescook@...omium.org>
---
crypto/tcrypt.c | 118 +++++++++++++++++++++++++++++++++++++-------------------
1 file changed, 79 insertions(+), 39 deletions(-)
diff --git a/crypto/tcrypt.c b/crypto/tcrypt.c
index 51fe7c8744ae..e721faab6fc8 100644
--- a/crypto/tcrypt.c
+++ b/crypto/tcrypt.c
@@ -158,9 +158,9 @@ struct test_mb_aead_data {
};
static int do_mult_aead_op(struct test_mb_aead_data *data, int enc,
- u32 num_mb)
+ u32 num_mb, int *rc)
{
- int i, rc[num_mb], err = 0;
+ int i, err = 0;
/* Fire up a bunch of concurrent requests */
for (i = 0; i < num_mb; i++) {
@@ -188,18 +188,26 @@ static int test_mb_aead_jiffies(struct test_mb_aead_data *data, int enc,
{
unsigned long start, end;
int bcount;
- int ret;
+ int ret = 0;
+ int *rc;
+
+ rc = kcalloc(num_mb, sizeof(*rc), GFP_KERNEL);
+ if (!rc)
+ return -ENOMEM;
for (start = jiffies, end = start + secs * HZ, bcount = 0;
time_before(jiffies, end); bcount++) {
- ret = do_mult_aead_op(data, enc, num_mb);
+ ret = do_mult_aead_op(data, enc, num_mb, rc);
if (ret)
- return ret;
+ goto out;
}
pr_cont("%d operations in %d seconds (%ld bytes)\n",
bcount * num_mb, secs, (long)bcount * blen * num_mb);
- return 0;
+
+out:
+ kfree(rc);
+ return ret;
}
static int test_mb_aead_cycles(struct test_mb_aead_data *data, int enc,
@@ -208,10 +216,15 @@ static int test_mb_aead_cycles(struct test_mb_aead_data *data, int enc,
unsigned long cycles = 0;
int ret = 0;
int i;
+ int *rc;
+
+ rc = kcalloc(num_mb, sizeof(*rc), GFP_KERNEL);
+ if (!rc)
+ return -ENOMEM;
/* Warm-up run. */
for (i = 0; i < 4; i++) {
- ret = do_mult_aead_op(data, enc, num_mb);
+ ret = do_mult_aead_op(data, enc, num_mb, rc);
if (ret)
goto out;
}
@@ -221,7 +234,7 @@ static int test_mb_aead_cycles(struct test_mb_aead_data *data, int enc,
cycles_t start, end;
start = get_cycles();
- ret = do_mult_aead_op(data, enc, num_mb);
+ ret = do_mult_aead_op(data, enc, num_mb, rc);
end = get_cycles();
if (ret)
@@ -230,11 +243,11 @@ static int test_mb_aead_cycles(struct test_mb_aead_data *data, int enc,
cycles += end - start;
}
-out:
- if (ret == 0)
- pr_cont("1 operation in %lu cycles (%d bytes)\n",
- (cycles + 4) / (8 * num_mb), blen);
+ pr_cont("1 operation in %lu cycles (%d bytes)\n",
+ (cycles + 4) / (8 * num_mb), blen);
+out:
+ kfree(rc);
return ret;
}
@@ -705,9 +718,10 @@ struct test_mb_ahash_data {
char *xbuf[XBUFSIZE];
};
-static inline int do_mult_ahash_op(struct test_mb_ahash_data *data, u32 num_mb)
+static inline int do_mult_ahash_op(struct test_mb_ahash_data *data, u32 num_mb,
+ int *rc)
{
- int i, rc[num_mb], err = 0;
+ int i, err = 0;
/* Fire up a bunch of concurrent requests */
for (i = 0; i < num_mb; i++)
@@ -731,18 +745,26 @@ static int test_mb_ahash_jiffies(struct test_mb_ahash_data *data, int blen,
{
unsigned long start, end;
int bcount;
- int ret;
+ int ret = 0;
+ int *rc;
+
+ rc = kcalloc(num_mb, sizeof(*rc), GFP_KERNEL);
+ if (!rc)
+ return -ENOMEM;
for (start = jiffies, end = start + secs * HZ, bcount = 0;
time_before(jiffies, end); bcount++) {
- ret = do_mult_ahash_op(data, num_mb);
+ ret = do_mult_ahash_op(data, num_mb, rc);
if (ret)
- return ret;
+ goto out;
}
pr_cont("%d operations in %d seconds (%ld bytes)\n",
bcount * num_mb, secs, (long)bcount * blen * num_mb);
- return 0;
+
+out:
+ kfree(rc);
+ return ret;
}
static int test_mb_ahash_cycles(struct test_mb_ahash_data *data, int blen,
@@ -751,10 +773,15 @@ static int test_mb_ahash_cycles(struct test_mb_ahash_data *data, int blen,
unsigned long cycles = 0;
int ret = 0;
int i;
+ int *rc;
+
+ rc = kcalloc(num_mb, sizeof(*rc), GFP_KERNEL);
+ if (!rc)
+ return -ENOMEM;
/* Warm-up run. */
for (i = 0; i < 4; i++) {
- ret = do_mult_ahash_op(data, num_mb);
+ ret = do_mult_ahash_op(data, num_mb, rc);
if (ret)
goto out;
}
@@ -764,7 +791,7 @@ static int test_mb_ahash_cycles(struct test_mb_ahash_data *data, int blen,
cycles_t start, end;
start = get_cycles();
- ret = do_mult_ahash_op(data, num_mb);
+ ret = do_mult_ahash_op(data, num_mb, rc);
end = get_cycles();
if (ret)
@@ -773,11 +800,11 @@ static int test_mb_ahash_cycles(struct test_mb_ahash_data *data, int blen,
cycles += end - start;
}
-out:
- if (ret == 0)
- pr_cont("1 operation in %lu cycles (%d bytes)\n",
- (cycles + 4) / (8 * num_mb), blen);
+ pr_cont("1 operation in %lu cycles (%d bytes)\n",
+ (cycles + 4) / (8 * num_mb), blen);
+out:
+ kfree(rc);
return ret;
}
@@ -1118,9 +1145,9 @@ struct test_mb_skcipher_data {
};
static int do_mult_acipher_op(struct test_mb_skcipher_data *data, int enc,
- u32 num_mb)
+ u32 num_mb, int *rc)
{
- int i, rc[num_mb], err = 0;
+ int i, err = 0;
/* Fire up a bunch of concurrent requests */
for (i = 0; i < num_mb; i++) {
@@ -1148,18 +1175,26 @@ static int test_mb_acipher_jiffies(struct test_mb_skcipher_data *data, int enc,
{
unsigned long start, end;
int bcount;
- int ret;
+ int ret = 0;
+ int *rc;
+
+ rc = kcalloc(num_mb, sizeof(*rc), GFP_KERNEL);
+ if (!rc)
+ return -ENOMEM;
for (start = jiffies, end = start + secs * HZ, bcount = 0;
time_before(jiffies, end); bcount++) {
- ret = do_mult_acipher_op(data, enc, num_mb);
+ ret = do_mult_acipher_op(data, enc, num_mb, rc);
if (ret)
- return ret;
+ goto out;
}
pr_cont("%d operations in %d seconds (%ld bytes)\n",
bcount * num_mb, secs, (long)bcount * blen * num_mb);
- return 0;
+
+out:
+ kfree(rc);
+ return ret;
}
static int test_mb_acipher_cycles(struct test_mb_skcipher_data *data, int enc,
@@ -1168,10 +1203,15 @@ static int test_mb_acipher_cycles(struct test_mb_skcipher_data *data, int enc,
unsigned long cycles = 0;
int ret = 0;
int i;
+ int *rc;
+
+ rc = kcalloc(num_mb, sizeof(*rc), GFP_KERNEL);
+ if (!rc)
+ return -ENOMEM;
/* Warm-up run. */
for (i = 0; i < 4; i++) {
- ret = do_mult_acipher_op(data, enc, num_mb);
+ ret = do_mult_acipher_op(data, enc, num_mb, rc);
if (ret)
goto out;
}
@@ -1181,7 +1221,7 @@ static int test_mb_acipher_cycles(struct test_mb_skcipher_data *data, int enc,
cycles_t start, end;
start = get_cycles();
- ret = do_mult_acipher_op(data, enc, num_mb);
+ ret = do_mult_acipher_op(data, enc, num_mb, rc);
end = get_cycles();
if (ret)
@@ -1190,11 +1230,11 @@ static int test_mb_acipher_cycles(struct test_mb_skcipher_data *data, int enc,
cycles += end - start;
}
-out:
- if (ret == 0)
- pr_cont("1 operation in %lu cycles (%d bytes)\n",
- (cycles + 4) / (8 * num_mb), blen);
+ pr_cont("1 operation in %lu cycles (%d bytes)\n",
+ (cycles + 4) / (8 * num_mb), blen);
+out:
+ kfree(rc);
return ret;
}
@@ -1606,7 +1646,7 @@ static inline int tcrypt_test(const char *alg)
return ret;
}
-static int do_test(const char *alg, u32 type, u32 mask, int m)
+static int do_test(const char *alg, u32 type, u32 mask, int m, u32 num_mb)
{
int i;
int ret = 0;
@@ -1621,7 +1661,7 @@ static int do_test(const char *alg, u32 type, u32 mask, int m)
}
for (i = 1; i < 200; i++)
- ret += do_test(NULL, 0, 0, i);
+ ret += do_test(NULL, 0, 0, i, num_mb);
break;
case 1:
@@ -2903,7 +2943,7 @@ static int __init tcrypt_mod_init(void)
goto err_free_tv;
}
- err = do_test(alg, type, mask, mode);
+ err = do_test(alg, type, mask, mode, num_mb);
if (err) {
printk(KERN_ERR "tcrypt: one or more tests failed!\n");
--
2.7.4
--
Kees Cook
Pixel Security
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