Merge #840: Return NULL early in context_preallocated_create if flags invalid

ebfa2058e9 Return NULL early in context_preallocated_create if flags invalid (Tim Ruffing)

Pull request description:

ACKs for top commit:
  sipa:
    ACK ebfa2058e9
  jonasnick:
    ACK ebfa2058e9

Tree-SHA512: 61310539046e015e5c9e6b5702ac7b542fda854a23915ef5dd549361c8ec6e70aa6d509e02b30fd859b24dfaf2250721bb55270767323d6e94854067b7d7e9a6
This commit is contained in:
Jonas Nick 2020-10-30 17:48:40 +00:00
commit 903b16aa6c
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1 changed files with 9 additions and 7 deletions

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@ -86,6 +86,8 @@ const secp256k1_context *secp256k1_context_no_precomp = &secp256k1_context_no_pr
size_t secp256k1_context_preallocated_size(unsigned int flags) {
size_t ret = ROUND_TO_ALIGN(sizeof(secp256k1_context));
/* A return value of 0 is reserved as an indicator for errors when we call this function internally. */
VERIFY_CHECK(ret != 0);
if (EXPECT((flags & SECP256K1_FLAGS_TYPE_MASK) != SECP256K1_FLAGS_TYPE_CONTEXT, 0)) {
secp256k1_callback_call(&default_illegal_callback,
@ -122,21 +124,21 @@ secp256k1_context* secp256k1_context_preallocated_create(void* prealloc, unsigne
if (!secp256k1_selftest()) {
secp256k1_callback_call(&default_error_callback, "self test failed");
}
VERIFY_CHECK(prealloc != NULL);
prealloc_size = secp256k1_context_preallocated_size(flags);
if (prealloc_size == 0) {
return NULL;
}
VERIFY_CHECK(prealloc != NULL);
ret = (secp256k1_context*)manual_alloc(&prealloc, sizeof(secp256k1_context), base, prealloc_size);
ret->illegal_callback = default_illegal_callback;
ret->error_callback = default_error_callback;
if (EXPECT((flags & SECP256K1_FLAGS_TYPE_MASK) != SECP256K1_FLAGS_TYPE_CONTEXT, 0)) {
secp256k1_callback_call(&ret->illegal_callback,
"Invalid flags");
return NULL;
}
secp256k1_ecmult_context_init(&ret->ecmult_ctx);
secp256k1_ecmult_gen_context_init(&ret->ecmult_gen_ctx);
/* Flags have been checked by secp256k1_context_preallocated_size. */
VERIFY_CHECK((flags & SECP256K1_FLAGS_TYPE_MASK) == SECP256K1_FLAGS_TYPE_CONTEXT);
if (flags & SECP256K1_FLAGS_BIT_CONTEXT_SIGN) {
secp256k1_ecmult_gen_context_build(&ret->ecmult_gen_ctx, &prealloc);
}