F-4936 - Take parent DRBG lock around raw dispatch calls - #454

Open

ColtonWilley wants to merge 1 commit into

wolfSSL:master from

ColtonWilley:fix/f_4936

Open

F-4936 - Take parent DRBG lock around raw dispatch calls #454
ColtonWilley wants to merge 1 commit into
wolfSSL:master from
ColtonWilley:fix/f_4936

Conversation

@ColtonWilley

@ColtonWilley ColtonWilley commented Jul 28, 2026

Copy link

Copy Markdown

Contributor

Child DRBGs called the parent's get_seed/clear_seed via raw dispatch pointers with no lock held, so concurrent child instantiations (e.g. two threads' first RAND_bytes) raced on the shared primary's WC_RNG.

Fix (mirrors OpenSSL's own PROV_DRBG):

capture parent ENABLE_LOCKING/LOCK/UNLOCK in newctx
take the parent lock around parentGetSeed/parentClearSeed
propagate enable_locking to the parent, one-shot; publish the local mutex only after init
scrub the seed in place if the clear_seed lock fails

F-5186 reviewed with this: works as designed — EVP_RAND locking is opt-in and core serializes generate/uninstantiate once enabled. Full suite green, default and --enable-seed-src.

@ColtonWilley


 F-4936 - Take parent DRBG lock around raw dispatch calls

e08e7ee

wp_drbg_instantiate called the parent's get_seed/clear_seed through raw
dispatch pointers with no lock, racing concurrent child instantiations
on the shared primary's WC_RNG. Capture the parent's locking dispatch
functions, wrap the parent calls, and propagate enable_locking one-shot,
mirroring OpenSSL's PROV_DRBG. F-5186 analyzed alongside: works as
designed under the EVP_RAND locking contract.

@ColtonWilley