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drbg: add thread-safe option, --disable-threadsafe-drbg to opt out - #11210

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kaleb-himes:DRBG-Threading
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drbg: add thread-safe option, --disable-threadsafe-drbg to opt out#11210
kaleb-himes wants to merge 12 commits into
wolfSSL:masterfrom
kaleb-himes:DRBG-Threading

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@kaleb-himes

@kaleb-himes kaleb-himes commented Aug 19, 2026

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Description

Feature addition

Testing

Test case added in wolfcrypt/test/test.c

Checklist

  • added tests
  • updated/added doxygen
  • updated appropriate READMEs
  • Updated manual and documentation

@kaleb-himes kaleb-himes self-assigned this Aug 19, 2026
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MemBrowse Memory Report

No memory changes detected for:

douzzer
douzzer previously requested changes Aug 20, 2026
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Comment thread wolfcrypt/src/random.c Outdated
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@MarkAtwood MarkAtwood mentioned this pull request Aug 20, 2026
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wolfSSL-Fenrir-bot dismissed stale reviews from themself August 22, 2026 06:04

Fenrir's latest completed scan found no issues; clearing the prior automated change request.

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kaleb-himes requested review from wolfSSL-Fenrir-bot and removed request for wolfSSL-Fenrir-bot September 5, 2026 17:20
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kaleb-himes requested review from wolfSSL-Fenrir-bot and removed request for wolfSSL-Fenrir-bot September 6, 2026 16:37
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@kaleb-himes
Add a per-instance lock so one WC_RNG can be shared between threads, …
d7835ed 
…with opt-in fork handlers
@kaleb-himes
Keep the RNG lock inline unless fork handlers need it on the heap
898ef9a
@kaleb-himes
Turn the RNG fork handlers on wherever pthread_atfork exists and pin …
884f85f 
…the library against dlclose
@kaleb-himes
Probe pthread_atfork and dladdr with real link tests in CMake
6f97c5b
@kaleb-himes
Include random.h in wc_port.c for every RNG build and probe the dlclo…
c2d7c4f 
…se pin by linking it
@kaleb-himes
Expect a reseeded child in the compat RAND test when the fork handler…
a093009 
…s are on
@kaleb-himes
Read dli_fname through a pointer, since Cygwin declares it as an array
2d17f5f
@kaleb-himes
Keep the FreeBSD sys/param.h include and define _GNU_SOURCE for the p…
dc4f753 
…in only where Cygwin needs it
@kaleb-himes
Check the forked child's RAND_bytes result and exit status in the com…
bf2c04d 
…pat RAND test
@kaleb-himes
Require the pin for the fork handlers, keep them out of user settings…
41b3c0b 
… and memory zero checking builds, and link dl only with the pin
@kaleb-himes
Reap the forked child before judging it and keep the zeroed free chec…
0c67dbb 
…k where the RNG is small
@kaleb-himes
Log a failed image pin, tidy the handler gates, and give the compat R…
e6e52e5 
…AND test its own includes
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wolfSSL-Fenrir-bot requested changes Sep 6, 2026
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Fenrir Automated Review — PR #11210

Scan targets checked: wolfcrypt-bugs, wolfcrypt-port-bugs, wolfcrypt-rs-bugs, wolfcrypt-src, wolfssl-bugs, wolfssl-src

Findings: 1
1 finding(s) posted as inline comments (see file-level comments below)

This review was generated automatically by Fenrir. Reported findings require changes before merge.

Comment thread wolfcrypt/src/random.c
if (ret != 0)
return ret;
if (!rngAtForkSet) {
if (pthread_atfork(RngAtForkPrepare, RngAtForkParent,

@wolfSSL-Fenrir-bot wolfSSL-Fenrir-bot Sep 6, 2026

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Fork handlers registered before the dlclose pin, and pin failure is ignored · Use-after-free / double-free

wc_RngAtForkInit() registers the irrevocable pthread_atfork handlers before pinning, and wc_RngPinImage() returns void and only logs on failure (including the build where RTLD_NODELETE/RTLD_NOLOAD are absent). If the pin fails, a dlclosed libwolfssl leaves the handlers pointing into unmapped memory, which the next fork() executes.

Fix: Pin the image before calling pthread_atfork(), have wc_RngPinImage() return a status, and skip registration when the pin fails.

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@wolfSSL-Fenrir-bot wolfSSL-Fenrir-bot wolfSSL-Fenrir-bot requested changes
@JacobBarthelmeh JacobBarthelmeh Awaiting requested review from JacobBarthelmeh
@wolfSSL-Bot wolfSSL-Bot Awaiting requested review from wolfSSL-Bot
@douzzer douzzer Awaiting requested review from douzzer

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