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Fix an EVP_MD_CTX leak

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If we initialise an EVP_MD_CTX with a legacy MD, and then reuse the same
EVP_MD_CTX with a provided MD then we end up leaking the md_data.

We need to ensure we free the md_data if we change to a provided MD.

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/12779)
This commit is contained in:
Matt Caswell 2020-09-03 11:50:30 +01:00 committed by Tomas Mraz
parent b830e00429
commit 3101ab603c
3 changed files with 38 additions and 21 deletions
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47
crypto/evp/digest.c
View File

@ -22,24 +22,9 @@
#include "internal/provider.h"
#include "evp_local.h"
/* This call frees resources associated with the context */
int EVP_MD_CTX_reset(EVP_MD_CTX *ctx)
void evp_md_ctx_clear_digest(EVP_MD_CTX *ctx, int force)
{
if (ctx == NULL)
return 1;
#ifndef FIPS_MODULE
/* TODO(3.0): Temporarily no support for EVP_DigestSign* in FIPS module */
/*
* pctx should be freed by the user of EVP_MD_CTX
* if EVP_MD_CTX_FLAG_KEEP_PKEY_CTX is set
*/
if (!EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_KEEP_PKEY_CTX)) {
EVP_PKEY_CTX_free(ctx->pctx);
ctx->pctx = NULL;
}
#endif
EVP_MD_free(ctx->fetched_digest);
ctx->fetched_digest = NULL;
ctx->reqdigest = NULL;
@ -61,16 +46,36 @@ int EVP_MD_CTX_reset(EVP_MD_CTX *ctx)
&& !EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_CLEANED))
ctx->digest->cleanup(ctx);
if (ctx->digest && ctx->digest->ctx_size && ctx->md_data
&& !EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_REUSE)) {
&& (!EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_REUSE) || force))
OPENSSL_clear_free(ctx->md_data, ctx->digest->ctx_size);
}
if (force)
ctx->digest = NULL;
#if !defined(FIPS_MODULE) && !defined(OPENSSL_NO_ENGINE)
ENGINE_finish(ctx->engine);
ctx->engine = NULL;
#endif
}
/* This call frees resources associated with the context */
int EVP_MD_CTX_reset(EVP_MD_CTX *ctx)
{
if (ctx == NULL)
return 1;
#ifndef FIPS_MODULE
/* TODO(3.0): Temporarily no support for EVP_DigestSign* in FIPS module */
/*
* pctx should be freed by the user of EVP_MD_CTX
* if EVP_MD_CTX_FLAG_KEEP_PKEY_CTX is set
*/
if (!EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_KEEP_PKEY_CTX)) {
EVP_PKEY_CTX_free(ctx->pctx);
ctx->pctx = NULL;
}
#endif
/* TODO(3.0): End of legacy code */
evp_md_ctx_clear_digest(ctx, 0);
OPENSSL_cleanse(ctx, sizeof(*ctx));
return 1;

10
crypto/evp/m_sigver.c
View File

@ -176,6 +176,12 @@ static int do_sigver_init(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
}
if (mdname != NULL) {
/*
* We're about to get a new digest so clear anything associated with
* an old digest.
*/
evp_md_ctx_clear_digest(ctx, 1);
/*
* This might be requested by a later call to EVP_MD_CTX_md().
* In that case the "explicit fetch" rules apply for that
@ -185,6 +191,10 @@ static int do_sigver_init(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
*/
ctx->digest = ctx->reqdigest = ctx->fetched_digest =
EVP_MD_fetch(locpctx->libctx, mdname, props);
if (ctx->digest == NULL) {
ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);
goto err;
}
}
}

2
include/crypto/evp.h
View File

@ -808,3 +808,5 @@ int evp_pkey_ctx_use_cached_data(EVP_PKEY_CTX *ctx);
void evp_method_store_flush(OPENSSL_CTX *libctx);
int evp_set_default_properties_int(OPENSSL_CTX *libctx, const char *propq,
int loadconfig);
void evp_md_ctx_clear_digest(EVP_MD_CTX *ctx, int force);