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Fix mutex double-free in RSA

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When MBEDTLS_THREADING_C is enabled, RSA code protects the use of the
key with a mutex. mbedtls_rsa_free() frees this mutex by calling
mbedtls_mutex_free(). This does not match the usage of
mbedtls_mutex_free(), which in general can only be done once.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2021-02-01 17:57:41 +01:00
parent 914afe1fdb
commit eb94059edd
1 changed files with 9 additions and 2 deletions
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11
library/rsa.c
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@ -490,6 +490,9 @@ void mbedtls_rsa_init( mbedtls_rsa_context *ctx,
mbedtls_rsa_set_padding( ctx, padding, hash_id );
#if defined(MBEDTLS_THREADING_C)
/* Set ctx->ver to nonzero to indicate that the mutex has been
* initialized and will need to be freed. */
ctx->ver = 1;
mbedtls_mutex_init( &ctx->mutex );
#endif
}
@ -2481,7 +2484,6 @@ int mbedtls_rsa_copy( mbedtls_rsa_context *dst, const mbedtls_rsa_context *src )
RSA_VALIDATE_RET( dst != NULL );
RSA_VALIDATE_RET( src != NULL );
dst->ver = src->ver;
dst->len = src->len;
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->N, &src->N ) );
@ -2540,7 +2542,12 @@ void mbedtls_rsa_free( mbedtls_rsa_context *ctx )
#endif /* MBEDTLS_RSA_NO_CRT */
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_free( &ctx->mutex );
/* Free the mutex, but only if it hasn't been freed already. */
if( ctx->ver != 0 )
{
mbedtls_mutex_free( &ctx->mutex );
ctx->ver = 0;
}
#endif
}