From: Sebastien Tardif via GitGitGadget Date: Wed, 27 May 2026 18:18:28 GMT Subject: [PATCH v2 0/3] daemon: fix network address handling bugs Message-ID: In-Reply-To: Fix three related issues in daemon.c's network address handling: IPv6 address corruption in lookup_hostname(): getaddrinfo() is called with AF_UNSPEC hints, so it may return IPv6 results. However, the code unconditionally casts ai_addr to sockaddr_in and passes AF_INET to inet_ntop(). On IPv6-only hosts, this reads from the wrong struct offset, producing garbage IP addresses. Fixed by checking ai_family and handling both AF_INET and AF_INET6. IPv6 address truncation in ip2str(): The sockaddr struct size (ai_addrlen) is passed as the output buffer size to inet_ntop(). For IPv6, sizeof(sockaddr_in6) is 28 bytes but INET6_ADDRSTRLEN is 46, so long IPv6 addresses are silently truncated. Fixed by passing sizeof(ip) instead, and dropping the now-unused len parameter. NULL pointer in execute() logging: REMOTE_PORT environment variable is used in a format string without a NULL check (only REMOTE_ADDR was checked). If REMOTE_PORT is unset, NULL is passed to printf's %s, which is undefined behavior. Fixed by using a fallback string. Changes since v1: * Split the single patch into three separate commits, one per fix, per Patrick's review. * Deduplicated the address family handling in lookup_hostname(): instead of duplicating the inet_ntop() call for each family, the address pointer is extracted into a local void *addr variable first, then inet_ntop() is called once, per Patrick's suggestion. * The (void *) intermediate cast on ai_addr is used intentionally: C guarantees any object pointer round-trips safely through void *, and it keeps the per-family blocks shorter than spelling out the full struct casts. * For the REMOTE_PORT NULL guard: both REMOTE_ADDR and REMOTE_PORT are set by the same code path in handle(), so neither should be NULL independently. The guard makes the code consistent with the existing REMOTE_ADDR check and avoids undefined behavior from printf %s with a NULL argument. * Die on unexpected address families in lookup_hostname() rather than silently leaving addrbuf uninitialized. Sebastien Tardif (3): daemon: fix IPv6 address corruption in lookup_hostname() daemon: fix IPv6 address truncation in ip2str() daemon: guard NULL REMOTE_PORT in execute() logging daemon.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) base-commit: 59ff4886a579f4bc91e976fe18590b9ae02c7a08 Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2300%2FSebTardif%2Ffix%2Fdaemon-ipv6-and-null-port-v2 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2300/SebTardif/fix/daemon-ipv6-and-null-port-v2 Pull-Request: https://github.com/git/git/pull/2300 Range-diff vs v1: 1: b2d8143811 = 1: b2d8143811 daemon: fix IPv6 address corruption in lookup_hostname() 2: 5c01ec3cad = 2: 5c01ec3cad daemon: fix IPv6 address truncation in ip2str() 3: 1b2f9d1a07 ! 3: e312735716 daemon: guard NULL REMOTE_PORT in execute() logging @@ Metadata ## Commit message ## daemon: guard NULL REMOTE_PORT in execute() logging - The REMOTE_PORT environment variable is used in a format string - without a NULL check, while REMOTE_ADDR is checked. If REMOTE_PORT - is unset, NULL is passed to printf's %s, which is undefined behavior. + REMOTE_ADDR and REMOTE_PORT are both set by the same code path in + handle(), so neither should be NULL independently. However, the + existing code checks REMOTE_ADDR before the loginfo() call but not + REMOTE_PORT. If REMOTE_PORT were unset, NULL would be passed to + printf's %s, which is undefined behavior. - Add a fallback string for the NULL case. + Add a fallback string for the NULL case, matching the existing + REMOTE_ADDR guard for consistency. Signed-off-by: Sebastien Tardif -- gitgitgadget