Fix Coverity Findings

[aidangarske]

Description

Dead Code (10 fixes)

• bsd_socket.c: Remove dead NULL check on pointer arithmetic result in wolfip_calc_msghdr_len
• bsd_socket.c: Remove dead else branches in send(), write(), and sendto() nonblock EAGAIN paths
• bsd_socket.c: Remove unreachable EAGAIN check in wolfIP_sock_recvmsg
• wolfip.c: Add comment explaining window scale loop is kept for larger buffer configs
• wolfip.c: Remove redundant if (!saw_end) before unconditional return -1 in dhcp_parse_ack
• tcp_echo.c, tcp_netcat_poll.c, tcp_netcat_select.c: Remove unreachable code after while(1) loops

Null Pointer Dereference (3 fixes)

• wolfip.c: Add NULL check after fifo_peek() in UDP recvfrom path
• bsd_socket.c: Add NULL check for wolfIP_getdev() return value in init_wolfip_posix
• test_wolfssl_forwarding.c: Add NULL check for wolfIP_getdev(server_stack)

Uninitialized Variable (1 fix)

• bsd_socket.c: Use calloc() instead of malloc() for heap_buf in wolfIP_sock_recvmsg

Integer Issues (3 fixes)

• wolfip.c: Explicit mask (~sum & 0xFFFF) in icmp_checksum
• test_ttl_expired.c: Explicit mask (~acc & 0xFFFF) in ones_csum
• wolfip.c: Guard modulo with if (f->size > 0) in fifo_align_tail

Buffer Overrun (2 fixes)

• wolfip.c: Add bounds check (pos + 4 > dns_len) before reading IP bytes in dns_callback
• wolfip.c: Add explicit frame buffer bounds check before ICMP memcpy in wolfIP_sock_sendto

Resource Leak (3 fixes)

• tap_linux.c: Close sock_fd at end of successful tap_init path
• test_dhcp_dns.c, test_eventloop.c, test_esp.c: Close listen and client fds on all pt_echoserver exit paths

Unchecked Return Values (4 fixes)

• bsd_socket.c: Check fcntl return values in wolfip_fd_alloc; close pipes on failure
• tcp_netcat_poll.c, tcp_netcat_select.c: Check send() return value
• test_dhcp_dns.c, test_eventloop.c, test_esp.c, test_native_wolfssl.c: Cast setsockopt to (void)

Thread Safety (4 fixes)

• bsd_socket.c: Re-fetch entry after unlock/relock in wolfip_accept_common
• bsd_socket.c: Re-fetch internal_fd after unlock/relock in sendto()
• bsd_socket.c: Add mutex lock around IPSTACK access in socket()
• bsd_socket.c: Lock mutex around IPSTACK init and configuration in init_wolfip_posix

Weak Crypto (1 fix)

• test_ttl_expired.c: Replace rand() with getrandom() (test-only code)

Negative Returns (2 fixes)

• tcp_echo.c, esp_server.c: Change socket() == 0 to socket() < 0

Tainted Data (1 fix)

• bsd_socket.c: Validate environment variable IP strings before passing to atoip4()

Buffer Not Null Terminated (1 fix)

• tap_linux.c: Null-terminate ifr.ifr_name after strncpy

None of these are CVE worthy fixes imo. The most security-relevant items (DNS/ICMP bounds, divide-by-zero, weak RNG) are bounded by internal protocol constraints or only affect test code. All fixes are defense-in-depth hardening.

[Copilot]

Pull request overview

This PR addresses a broad set of Coverity findings across the wolfIP core, POSIX port layer, and test utilities, focusing on removing dead/unreachable code and hardening error handling and bounds checks.

Changes:

• Harden wolfIP core logic with additional bounds checks, integer masking, and defensive guards.
• Improve POSIX wrapper correctness (thread-safety locking, fd allocation error handling, env var validation).
• Fix test utilities for resource cleanup, unchecked return values, and weak RNG usage.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/wolfip.c	Adds safety guards (modulo-by-zero, bounds checks), checksum masking, and small logic cleanups.
src/port/posix/bsd_socket.c	Adds fcntl error checking, mutex protection for socket/init paths, env IP validation, and dead-code cleanup.
src/port/posix/tap_linux.c	Ensures ifname null-termination and closes sock_fd on successful init.
src/test/test_wolfssl_forwarding.c	Adds NULL check around wolfIP_getdev() usage.
src/test/test_ttl_expired.c	Switches RNG to getrandom() with fallback; checksum masking.
src/test/test_native_wolfssl.c	Explicitly ignores setsockopt return value.
src/test/test_eventloop.c	Ensures fd cleanup on error/exit paths; ignores setsockopt return value.
src/test/test_dhcp_dns.c	Ensures fd cleanup on error/exit paths; ignores setsockopt return value.
src/test/tcp_netcat_select.c	Checks send() return value; removes unreachable cleanup.
src/test/tcp_netcat_poll.c	Checks send() return value; removes unreachable cleanup.
src/test/tcp_echo.c	Fixes socket() failure check; removes unreachable cleanup.
src/test/esp/test_esp.c	Ensures fd cleanup on error/exit paths; ignores setsockopt return value.
src/test/esp/esp_server.c	Fixes socket() failure check.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[danielinux]

nit: remove comment on default rwnd, that's config-specific, while the code covers all cases.

[Copilot]

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 4 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.