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Fix NULL Checks and Error Handling #527

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Fix NULL Checks and Error Handling #527

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6228c88
Fix NULL Check and Error Handling
songlingatpan Sep 25, 2024
501f6e5
Fix NULL Check and Error Handling
songlingatpan Sep 25, 2024
4b2017c
Fix potential memory leak
songlingatpan Sep 25, 2024
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20 changes: 12 additions & 8 deletions oqsprov/oqs_kem.c
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Original file line number Diff line number Diff line change
Expand Up @@ -67,19 +67,23 @@ static void oqs_kem_freectx(void *vpkemctx) {
PROV_OQSKEM_CTX *pkemctx = (PROV_OQSKEM_CTX *)vpkemctx;

OQS_KEM_PRINTF("OQS KEM provider called: freectx\n");
oqsx_key_free(pkemctx->kem);
OPENSSL_free(pkemctx);
if (pkemctx != NULL) {
oqsx_key_free(pkemctx->kem);
OPENSSL_free(pkemctx);
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Same comment as below: OPENSSL_free handles NULL gracefully, and imo it's cleaner to not perform the check.

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The NULL check is for prevent from NULL pointer for oqsx_key_free(pkemctx->kem), not for OPENSSL_free/free().

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Ah yes, I should have been more clear: I meant to write that the OPENSSL_free call could be moved outside the conditional block, not that the check itself could be removed entirely. Certainly it's still necessary before the dereference.

}
}

static int oqs_kem_decapsencaps_init(void *vpkemctx, void *vkem,
int operation) {
PROV_OQSKEM_CTX *pkemctx = (PROV_OQSKEM_CTX *)vpkemctx;

OQS_KEM_PRINTF3("OQS KEM provider called: _init : New: %p; old: %p \n",
vkem, pkemctx->kem);
vkem, pkemctx ? pkemctx->kem : NULL);
if (pkemctx == NULL || vkem == NULL || !oqsx_key_up_ref(vkem))
return 0;
oqsx_key_free(pkemctx->kem);
if (pkemctx->kem != NULL) {
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There's nothing technically wrong with putting this guard here, but it's not necessary—oqsx_key_free handles null pointers gracefully, as (in my opinion) any "good" freeing function should. I would vote to remove the guard and add a comment above the oqsx_key_free function stating that it must handle NULL.

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Thanks for the comments.
We see quite some crashes due to dereference NULL pointer in our load testing. That is why we aggressively add NULL checks.
I will remove unnecessary NULL checks.

oqsx_key_free(pkemctx->kem);
}
pkemctx->kem = vkem;

return 1;
Expand All @@ -106,13 +110,13 @@ static int oqs_qs_kem_encaps_keyslot(void *vpkemctx, unsigned char *out,
const OQS_KEM *kem_ctx = NULL;

OQS_KEM_PRINTF("OQS KEM provider called: encaps\n");
if (pkemctx->kem == NULL) {
if (pkemctx == NULL || pkemctx->kem == NULL) {
OQS_KEM_PRINTF("OQS Warning: OQS_KEM not initialized\n");
return -1;
}

kem_ctx = pkemctx->kem->oqsx_provider_ctx.oqsx_qs_ctx.kem;
if (pkemctx->kem->comp_pubkey == NULL ||
if (kem_ctx == NULL || pkemctx->kem->comp_pubkey == NULL ||
pkemctx->kem->comp_pubkey[keyslot] == NULL) {
OQS_KEM_PRINTF("OQS Warning: public key is NULL\n");
return -1;
Expand Down Expand Up @@ -156,12 +160,12 @@ static int oqs_qs_kem_decaps_keyslot(void *vpkemctx, unsigned char *out,
const OQS_KEM *kem_ctx = NULL;

OQS_KEM_PRINTF("OQS KEM provider called: decaps\n");
if (pkemctx->kem == NULL) {
if (pkemctx == NULL || pkemctx->kem == NULL) {
OQS_KEM_PRINTF("OQS Warning: OQS_KEM not initialized\n");
return -1;
}
kem_ctx = pkemctx->kem->oqsx_provider_ctx.oqsx_qs_ctx.kem;
if (pkemctx->kem->comp_privkey == NULL ||
if (kem_ctx == NULL || pkemctx->kem->comp_privkey == NULL ||
pkemctx->kem->comp_privkey[keyslot] == NULL) {
OQS_KEM_PRINTF("OQS Warning: private key is NULL\n");
return -1;
Expand Down
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