Use O_CLOEXEC to avoid race conditions by embhorn · Pull Request #10162 · wolfSSL/wolfssl

embhorn · 2026-04-08T12:29:07Z

Description

Use the "close-on-exec" flag at file creation time to harden multithread use cases against race conditions.

Fixes #9753

Testing

build testing

Checklist

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

Copilot

Pull request overview

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Hardens file-descriptor creation against FD leaks across fork()+exec() in multithreaded programs by using close-on-exec flags (e.g., O_CLOEXEC, SOCK_CLOEXEC, EFD_CLOEXEC) at creation time where possible.

Changes:

Introduces portable WC_*_CLOEXEC macros that fall back to no-ops on unsupported platforms.
Applies WC_CLOEXEC / WC_SOCK_CLOEXEC / WC_EFD_CLOEXEC to various open(), socket(), and eventfd() call sites.
Uses accept4(..., SOCK_CLOEXEC) for AF_ALG where available and passes close-on-exec flag to perf_event_open.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
wolfssl/wolfcrypt/wc_port.h	Adds portable close-on-exec flag macros for FD-creating syscalls.
wolfcrypt/src/random.c	Opens RNG-related device FDs with `O_CLOEXEC` where available.
wolfcrypt/src/port/intel/quickassist_mem.c	Opens QAT memory device with `O_CLOEXEC`.
wolfcrypt/src/port/devcrypto/wc_devcrypto.c	Opens `/dev/crypto` with `O_CLOEXEC`.
wolfcrypt/src/port/caam/wolfcaam_qnx.c	Opens CAAM device with `O_CLOEXEC`.
wolfcrypt/src/port/af_alg/wc_afalg.c	Uses `accept4(..., SOCK_CLOEXEC)` when available; creates AF_ALG sockets with `SOCK_CLOEXEC`.
wolfcrypt/src/port/af_alg/afalg_hash.c	Uses `accept4(..., SOCK_CLOEXEC)` when available for duplicated AF_ALG FDs.
wolfcrypt/benchmark/benchmark.c	Adds `PERF_FLAG_FD_CLOEXEC` to `perf_event_open` flags.
src/wolfio.c	Creates TCP sockets with `SOCK_CLOEXEC`; sets `FD_CLOEXEC` after `accept()`.
src/ssl.c	Creates EGD AF_UNIX socket with `SOCK_CLOEXEC`.
src/crl.c	Uses CLOEXEC flags for `eventfd`/`inotify`/`open()` in CRL monitor paths.

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Copilot

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 5 comments.

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dgarske

🐺 Skoll Code Review

Overall recommendation: REQUEST_CHANGES
Findings: 5 total — 4 posted, 1 skipped

Posted findings

[Low] crl.c kqueue path: F_SETFD without read-modify-write — src/crl.c:1719
[Low] wolfio.c: defined(SOCK_CLOEXEC) guard in accept4 path is tautologically true — src/wolfio.c:1642-1643
[Medium] afalg_hash.c: accept4 used without _GNU_SOURCE but guarded by system SOCK_CLOEXEC — wolfcrypt/src/port/af_alg/afalg_hash.c:226-232
[High] wolfio.c: _GNU_SOURCE placement may conflict if libwolfssl_sources.h pulls in system headers — src/wolfio.c:31-36

Skipped findings

[Medium] wc_afalg.c: SOCK_CLOEXEC fallback defeats accept4 guard — missing _GNU_SOURCE

Review generated by Skoll via openclaw

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10162

Scan targets checked: wolfcrypt-api_misuse, wolfcrypt-bugs, wolfcrypt-compliance, wolfcrypt-concurrency, wolfcrypt-consttime, wolfcrypt-defaults, wolfcrypt-mutation, wolfcrypt-port, wolfcrypt-port-bugs, wolfcrypt-portability, wolfcrypt-proptest, wolfcrypt-src, wolfcrypt-zeroize, wolfssl-bugs, wolfssl-compliance, wolfssl-consttime, wolfssl-defaults, wolfssl-mutation, wolfssl-proptest, wolfssl-src, wolfssl-zeroize

Findings: 3
3 finding(s) posted as inline comments (see file-level comments below)

This review was generated automatically by Fenrir. Findings are non-blocking.

Copilot

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 5 comments.

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wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10162

Scan targets checked: wolfcrypt-api_misuse, wolfcrypt-bugs, wolfcrypt-compliance, wolfcrypt-concurrency, wolfcrypt-consttime, wolfcrypt-defaults, wolfcrypt-mutation, wolfcrypt-port, wolfcrypt-port-bugs, wolfcrypt-portability, wolfcrypt-proptest, wolfcrypt-src, wolfcrypt-zeroize, wolfssl-bugs, wolfssl-compliance, wolfssl-consttime, wolfssl-defaults, wolfssl-mutation, wolfssl-proptest, wolfssl-src, wolfssl-zeroize

No new issues found in the changed files. ✅

Copilot

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

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github-actions · 2026-04-17T16:33:33Z

MemBrowse Memory Report

gcc-arm-cortex-m4

FLASH: .text +64 B (+0.0%, 195,403 B / 262,144 B, total: 75% used)

gcc-arm-cortex-m4-min-ecc

FLASH: .text +64 B (+0.1%, 59,189 B / 262,144 B, total: 23% used)

gcc-arm-cortex-m4-tls12

FLASH: .text +64 B (+0.1%, 119,482 B / 262,144 B, total: 46% used)
No memory changes detected for:
gcc-arm-cortex-m4-baremetal

ColtonWilley · 2026-04-20T12:13:46Z

Jenkins retest this please

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10162

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

Findings: 2
2 finding(s) posted as inline comments (see file-level comments below)

This review was generated automatically by Fenrir. Findings are non-blocking.

douzzer · 2026-04-20T23:00:48Z

retest this please

wolfSSL error: tcp bind failed: Address already in use

douzzer · 2026-04-20T23:15:18Z

retest this please
(possible true positive -- wolfSSL error: tcp bind failed: Address already in use
in ocsp-stapling2.test)

douzzer

The hardcoded fallback SO_REUSEPORT is absolutely atrocious but we can fix that at a later date :-)

socketpair · 2026-04-25T04:16:00Z

        SignalSetup(crl, MONITOR_SETUP_E);
        return NULL;
    }
+    wc_set_cloexec(crl->mfd);


No, solution is racy. Use kqueue1()

socketpair · 2026-04-25T04:20:44Z

 */

+#if defined(__linux__) && !defined(_GNU_SOURCE)
+    #define _GNU_SOURCE 1


Move that please to the global build config (in order to use this definition for all files in the project).

socketpair · 2026-04-25T04:26:07Z

+    int fdFlags;
+    if (fd < 0)
+        return;
+    fdFlags = fcntl(fd, F_GETFD);


Under linux there is a faster alternative: int result = ioctl(fd, FIOCLEX);
(If supported) See CPython sources. Really faster you may benchmark.

socketpair · 2026-04-25T04:31:32Z

+ * (no _DEFAULT_SOURCE/__USE_MISC). Fall back to the Linux numeric value
+ * so concurrent binds on the same port remain supported. */
+#if defined(__linux__) && !defined(SO_REUSEPORT)
+    #define SO_REUSEPORT 15


Are you sure the value is the same on all cpu architectures?

socketpair · 2026-04-25T04:37:06Z

    static THREAD_LS_T int cycles = -1;
    static THREAD_LS_T struct perf_event_attr atr;

+    /* Try with PERF_FLAG_FD_CLOEXEC first; on older kernels (< 3.14) this


Do we need to support ancient kernels ? Why not to drop support for too old kernels/headers ?

embhorn self-assigned this Apr 8, 2026

embhorn added the Not For This Release Not for release 5.9.1 label Apr 8, 2026

Copilot AI review requested due to automatic review settings April 8, 2026 12:29

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Comment thread wolfcrypt/benchmark/benchmark.c

Comment thread src/wolfio.c Outdated

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Comment thread wolfcrypt/src/port/af_alg/wc_afalg.c Outdated

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Comment thread wolfssl/wolfcrypt/wc_port.h Outdated

Comment thread wolfcrypt/benchmark/benchmark.c Outdated

Comment thread src/wolfio.c Outdated

Comment thread src/wolfio.c Outdated

Comment thread src/crl.c

embhorn assigned wolfSSL-Bot and unassigned embhorn Apr 9, 2026

dgarske requested changes Apr 9, 2026

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Comment thread src/crl.c Outdated

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Comment thread wolfcrypt/src/port/af_alg/afalg_hash.c Outdated

Comment thread src/wolfio.c Outdated

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embhorn removed the Not For This Release Not for release 5.9.1 label Apr 10, 2026

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embhorn force-pushed the gh9753 branch from 8820776 to b730887 Compare April 13, 2026 19:34

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embhorn requested a review from wolfSSL-Fenrir-bot April 13, 2026 21:13

embhorn force-pushed the gh9753 branch from b730887 to 72e3af9 Compare April 14, 2026 12:33

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Comment thread src/wolfio.c Outdated

Comment thread src/ssl.c Outdated

Comment thread wolfcrypt/src/port/devcrypto/wc_devcrypto.c Outdated

Comment thread wolfcrypt/src/port/intel/quickassist_mem.c Outdated

Comment thread wolfcrypt/src/port/caam/wolfcaam_qnx.c Outdated

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douzzer removed their assignment Apr 16, 2026

embhorn dismissed stale reviews from dgarske and SparkiDev via 7aab6e5 April 17, 2026 14:38

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Comment thread wolfssl/wolfcrypt/wc_port.h

Comment thread wolfcrypt/src/wc_port.c

embhorn force-pushed the gh9753 branch from 8844a1f to 356bb59 Compare April 17, 2026 15:28

Use O_CLOEXEC to avoid race conditions

e26ab42

embhorn force-pushed the gh9753 branch from cfe3037 to e26ab42 Compare April 17, 2026 16:14

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Comment thread wolfcrypt/src/port/caam/wolfcaam_qnx.c

Comment thread src/crl.c

embhorn added 2 commits April 20, 2026 08:22

Fix from review

1b5d77e

Fix from review

fb7e1aa

Fix latent test issue found with the PR

2dc0076

douzzer approved these changes Apr 21, 2026

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douzzer unassigned embhorn Apr 21, 2026

This was referenced Apr 23, 2026

[Bug]: many open() without O_CLOEXEC #9753

Closed

user-src code review: missing FD_CLOEXEC + minor cleanup items wolfSSL/wolfGuard#23

Open

JacobBarthelmeh approved these changes Apr 24, 2026

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JacobBarthelmeh merged commit 0c9a496 into wolfSSL:master Apr 24, 2026
451 of 452 checks passed

embhorn deleted the gh9753 branch April 24, 2026 21:24

socketpair reviewed Apr 25, 2026

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embhorn commented Apr 8, 2026

Description

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MemBrowse Memory Report

gcc-arm-cortex-m4

gcc-arm-cortex-m4-min-ecc

gcc-arm-cortex-m4-tls12

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