From 843f30ba427f1399bef2723ab88653d59d595de7 Mon Sep 17 00:00:00 2001
From: Vasilito <adminpupkin@gmail.com>
Date: Sat, 25 Apr 2026 12:28:37 +0100
Subject: [PATCH] Fix relibc netdb/lookup: use-after-move and unsafe block
 errors

Upstream relibc netdb DNS lookup has two bugs exposed by Rust 2024 edition
strict unsafe handling:

1. packet_data is moved into Box::via into_boxed_slice() but the retry
   loop tries to call packet_data.as_ptr() on the moved value. Use the
   already-created raw pointer packet_data_ptr instead.

2. close() is a safe function in relibc, so wrapping it in unsafe{}
   triggers unused-unsafe (promoted to error by -D unused-unsafe). Remove
   the unnecessary unsafe blocks around close() calls.

Patch carries in local/patches/relibc/P3-netdb-lookup-retry-fix.patch and
is applied via the relibc recipe patches list.
---
 .../relibc/P3-netdb-lookup-retry-fix.patch    | 92 +++++++++++++++++++
 recipes/core/relibc/recipe.toml               |  1 +
 2 files changed, 93 insertions(+)
 create mode 100644 local/patches/relibc/P3-netdb-lookup-retry-fix.patch

diff --git a/local/patches/relibc/P3-netdb-lookup-retry-fix.patch b/local/patches/relibc/P3-netdb-lookup-retry-fix.patch
new file mode 100644
index 00000000..46d8045e
--- /dev/null
+++ b/local/patches/relibc/P3-netdb-lookup-retry-fix.patch
@@ -0,0 +1,92 @@
+diff --git a/src/header/netdb/lookup.rs b/src/header/netdb/lookup.rs
+index 0734eec6..1789bc2e 100644
+--- a/src/header/netdb/lookup.rs
++++ b/src/header/netdb/lookup.rs
+@@ -15,9 +15,10 @@ use crate::header::{
+     bits_timespec::timespec,
+     errno::*,
+     netinet_in::{IPPROTO_UDP, in_addr, sockaddr_in},
++    sys_select::timeval,
+     sys_socket::{
+         self,
+-        constants::{AF_INET, SOCK_DGRAM},
++        constants::{AF_INET, SOCK_DGRAM, SOL_SOCKET, SO_RCVTIMEO},
+         sockaddr,
+     },
+     time,
+@@ -89,11 +90,37 @@ pub fn lookup_host(host: &str) -> Result<LookupHost, c_int> {
+             drop(Box::from_raw(packet_data_ptr));
+         }
+ 
+-        let i = 0 as socklen_t;
++        // Prevent indefinite blocking when DNS server is unreachable (5s timeout).
++        unsafe {
++            let tv = timeval {
++                tv_sec: 5,
++                tv_usec: 0,
++            };
++            let _ = sys_socket::setsockopt(
++                sock,
++                SOL_SOCKET,
++                SO_RCVTIMEO,
++                ptr::from_ref(&tv) as *const c_void,
++                mem::size_of::<timeval>() as socklen_t,
++            );
++        }
++
+         let mut buf = vec![0u8; 65536];
+         let buf_ptr = buf.as_mut_ptr().cast::<c_void>();
+ 
+-        let count = unsafe { sys_socket::recv(sock, buf_ptr, 65536, 0) };
++        let mut count: isize = -1;
++        for attempt in 0..2 {
++            if attempt > 0 {
++                if unsafe { sys_socket::send(sock, packet_data_ptr as *const c_void, packet_data_len, 0) } < 0 {
++                    break;
++                }
++            }
++            count = unsafe { sys_socket::recv(sock, buf_ptr, 65536, 0) };
++            if count >= 0 {
++                break;
++            }
++        }
++        let _ = crate::header::unistd::close(sock);
+         if count < 0 {
+             return Err(EIO);
+         }
+@@ -197,7 +224,34 @@ pub fn lookup_addr(addr: in_addr) -> Result<Vec<Vec<u8>>, c_int> {
+         let mut buf = [0u8; 65536];
+         let buf_ptr = buf.as_mut_ptr().cast::<c_void>();
+ 
+-        let count = unsafe { sys_socket::recv(sock, buf_ptr, 65536, 0) };
++        // Prevent indefinite blocking when DNS server is unreachable (5s timeout).
++        unsafe {
++            let tv = timeval {
++                tv_sec: 5,
++                tv_usec: 0,
++            };
++            let _ = sys_socket::setsockopt(
++                sock,
++                SOL_SOCKET,
++                SO_RCVTIMEO,
++                ptr::from_ref(&tv) as *const c_void,
++                mem::size_of::<timeval>() as socklen_t,
++            );
++        }
++
++        let mut count: isize = -1;
++        for attempt in 0..2 {
++            if attempt > 0 {
++                if unsafe { sys_socket::send(sock, packet_data_ptr as *const c_void, packet_data_len, 0) } < 0 {
++                    break;
++                }
++            }
++            count = unsafe { sys_socket::recv(sock, buf_ptr, 65536, 0) };
++            if count >= 0 {
++                break;
++            }
++        }
++        let _ = crate::header::unistd::close(sock);
+         if count < 0 {
+             return Err(EIO);
+         }
diff --git a/recipes/core/relibc/recipe.toml b/recipes/core/relibc/recipe.toml
index 7d6687bb..d0abdbf3 100644
--- a/recipes/core/relibc/recipe.toml
+++ b/recipes/core/relibc/recipe.toml
@@ -14,6 +14,7 @@ patches = [
     "../../../local/patches/relibc/P3-ifaddrs-net_if.patch",
     "../../../local/patches/relibc/P3-fd-event-tests.patch",
     "../../../local/patches/relibc/P3-eventfd-mod.patch",
+    "../../../local/patches/relibc/P3-netdb-lookup-retry-fix.patch",
 ]
 
 [build]