Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
crypto: null - Use spin lock instead of mutex
As the null algorithm may be freed in softirq context through
af_alg, use spin locks instead of mutexes to protect the default
null algorithm.
Reported-by: syzbot+b3e02953598f447d4d2a@syzkaller.appspotmail.com
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
+25
-12
+25
-12
crypto/crypto_null.c
+25
-12
crypto/crypto_null.c
···
17
17
#include <crypto/internal/skcipher.h>
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#include <linux/init.h>
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#include <linux/module.h>
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-
#include <linux/mm.h>
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+
#include <linux/spinlock.h>
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#include <linux/string.h>
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-
static DEFINE_MUTEX(crypto_default_null_skcipher_lock);
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+
static DEFINE_SPINLOCK(crypto_default_null_skcipher_lock);
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static struct crypto_sync_skcipher *crypto_default_null_skcipher;
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static int crypto_default_null_skcipher_refcnt;
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26
···
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struct crypto_sync_skcipher *crypto_get_default_null_skcipher(void)
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{
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+
struct crypto_sync_skcipher *ntfm = NULL;
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struct crypto_sync_skcipher *tfm;
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-
mutex_lock(&crypto_default_null_skcipher_lock);
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+
spin_lock_bh(&crypto_default_null_skcipher_lock);
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tfm = crypto_default_null_skcipher;
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if (!tfm) {
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-
tfm = crypto_alloc_sync_skcipher("ecb(cipher_null)", 0, 0);
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-
if (IS_ERR(tfm))
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-
goto unlock;
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+
spin_unlock_bh(&crypto_default_null_skcipher_lock);
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-
crypto_default_null_skcipher = tfm;
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+
ntfm = crypto_alloc_sync_skcipher("ecb(cipher_null)", 0, 0);
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+
if (IS_ERR(ntfm))
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+
return ntfm;
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+
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+
spin_lock_bh(&crypto_default_null_skcipher_lock);
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+
tfm = crypto_default_null_skcipher;
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+
if (!tfm) {
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+
tfm = ntfm;
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+
ntfm = NULL;
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+
crypto_default_null_skcipher = tfm;
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+
}
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}
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176
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crypto_default_null_skcipher_refcnt++;
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+
spin_unlock_bh(&crypto_default_null_skcipher_lock);
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-
unlock:
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-
mutex_unlock(&crypto_default_null_skcipher_lock);
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+
crypto_free_sync_skcipher(ntfm);
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return tfm;
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}
···
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void crypto_put_default_null_skcipher(void)
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{
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-
mutex_lock(&crypto_default_null_skcipher_lock);
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+
struct crypto_sync_skcipher *tfm = NULL;
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+
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+
spin_lock_bh(&crypto_default_null_skcipher_lock);
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if (!--crypto_default_null_skcipher_refcnt) {
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-
crypto_free_sync_skcipher(crypto_default_null_skcipher);
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+
tfm = crypto_default_null_skcipher;
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184
crypto_default_null_skcipher = NULL;
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185
}
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-
mutex_unlock(&crypto_default_null_skcipher_lock);
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+
spin_unlock_bh(&crypto_default_null_skcipher_lock);
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+
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+
crypto_free_sync_skcipher(tfm);
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}
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EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher);
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