From adafd67028e34fd8570c4dc74edac66c41b108fa Mon Sep 17 00:00:00 2001
From: mintsuki <mintsuki@protonmail.com>
Date: Thu, 11 Jul 2024 02:26:50 +0200
Subject: [PATCH] host/limine: Protect against overwriting beginning of
 partitions located too low

---
 host/limine.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/host/limine.c b/host/limine.c
index 5bb60c32..62c930c4 100644
--- a/host/limine.c
+++ b/host/limine.c
@@ -712,6 +712,7 @@ static int bios_install(int argc, char *argv[]) {
 
         uint8_t hint8 = 0;
         uint16_t hint16 = 0;
+        uint32_t hint32 = 0;
 
         bool any_active = false;
 
@@ -725,6 +726,14 @@ static int bios_install(int argc, char *argv[]) {
             }
         }
         any_active = any_active || (hint8 & 0x80) != 0;
+        device_read(&hint8, 446 + 4, sizeof(uint8_t));
+        if (hint8 != 0x00) {
+            device_read(&hint32, 446 + 8, sizeof(uint32_t));
+            hint32 = ENDSWAP(hint32);
+            if (hint32 < 63) {
+                goto part_too_low;
+            }
+        }
         device_read(&hint8, 462, sizeof(uint8_t));
         if (hint8 != 0x00 && hint8 != 0x80) {
             if (!force_mbr) {
@@ -735,6 +744,14 @@ static int bios_install(int argc, char *argv[]) {
             }
         }
         any_active = any_active || (hint8 & 0x80) != 0;
+        device_read(&hint8, 462 + 4, sizeof(uint8_t));
+        if (hint8 != 0x00) {
+            device_read(&hint32, 462 + 8, sizeof(uint32_t));
+            hint32 = ENDSWAP(hint32);
+            if (hint32 < 63) {
+                goto part_too_low;
+            }
+        }
         device_read(&hint8, 478, sizeof(uint8_t));
         if (hint8 != 0x00 && hint8 != 0x80) {
             if (!force_mbr) {
@@ -745,6 +762,14 @@ static int bios_install(int argc, char *argv[]) {
             }
         }
         any_active = any_active || (hint8 & 0x80) != 0;
+        device_read(&hint8, 478 + 4, sizeof(uint8_t));
+        if (hint8 != 0x00) {
+            device_read(&hint32, 478 + 8, sizeof(uint32_t));
+            hint32 = ENDSWAP(hint32);
+            if (hint32 < 63) {
+                goto part_too_low;
+            }
+        }
         device_read(&hint8, 494, sizeof(uint8_t));
         if (hint8 != 0x00 && hint8 != 0x80) {
             if (!force_mbr) {
@@ -755,6 +780,20 @@ static int bios_install(int argc, char *argv[]) {
             }
         }
         any_active = any_active || (hint8 & 0x80) != 0;
+        device_read(&hint8, 494 + 4, sizeof(uint8_t));
+        if (hint8 != 0x00) {
+            device_read(&hint32, 494 + 8, sizeof(uint32_t));
+            hint32 = ENDSWAP(hint32);
+            if (hint32 < 63) {
+                goto part_too_low;
+            }
+        }
+
+        if (0) {
+part_too_low:
+            fprintf(stderr, "%s: error: A partition's start sector is less than 63, aborting.\n", program_name);
+            goto cleanup;
+        }
 
         char hintc[64];
         device_read(hintc, 4, 8);