Fixed unchecked fseek calls in 'boot' program (CWE-252)

IF the image and boot files are truncated or corrupt, these
fseek files will fail however without checking them, we will
read or write subsequent garbage.

This commit checks the fseek result code and will log and
close the file on failure.

src/dos/program_boot.cpp

@@ -30,6 +30,7 @@
 #include "cross.h"
 #include "dma.h"
 #include "drives.h"
+#include "fs_utils.h"
 #include "mapper.h"
 #include "program_more_output.h"
 #include "regs.h"
@@ -62,7 +63,10 @@ FILE* BOOT::getFSFile_mounted(const char* filename, uint32_t* ksize,
 		}
 
 		// get file size
-		fseek(tmpfile, 0L, SEEK_END);
+		if (!check_fseek("BOOT", "image", filename, tmpfile, 0L, SEEK_END)) {
+			return nullptr;
+		}
+
 		*ksize = (ftell(tmpfile) / 1024);
 		*bsize = ftell(tmpfile);
 		fclose(tmpfile);
@@ -96,14 +100,19 @@ FILE* BOOT::getFSFile(const char* filename, uint32_t* ksize, uint32_t* bsize,
 	// File not found on mounted filesystem. Try regular filesystem
 	const auto filename_s = resolve_home(filename).string();
 	tmpfile = fopen_wrap(filename_s.c_str(), "rb+");
+
+	auto fseek_in_tmpfile = make_check_fseek_func("BOOT", "image", filename);
+
 	if (!tmpfile) {
 		if ((tmpfile = fopen_wrap(filename_s.c_str(), "rb"))) {
 			// File exists; So can't be opened in correct mode =>
 			// error 2
 			//				fclose(tmpfile);
 			//				if (tryload) error = 2;
 			WriteOut(MSG_Get("PROGRAM_BOOT_WRITE_PROTECTED"));
-			fseek(tmpfile, 0L, SEEK_END);
+			if (!fseek_in_tmpfile(tmpfile, 0L, SEEK_END)) {
+				return nullptr;
+			}
 			*ksize = (ftell(tmpfile) / 1024);
 			*bsize = ftell(tmpfile);
 			return tmpfile;
@@ -116,7 +125,9 @@ FILE* BOOT::getFSFile(const char* filename, uint32_t* ksize, uint32_t* bsize,
 			WriteOut(MSG_Get("PROGRAM_BOOT_NOT_OPEN"));
 		return nullptr;
 	}
-	fseek(tmpfile, 0L, SEEK_END);
+	if (!fseek_in_tmpfile(tmpfile, 0L, SEEK_END)) {
+		return nullptr;
+	}
 	*ksize = (ftell(tmpfile) / 1024);
 	*bsize = ftell(tmpfile);
 	return tmpfile;
@@ -274,16 +285,18 @@ void BOOT::Run(void)
 		} else {
 			uint8_t rombuf[65536];
 			Bits cfound_at = -1;
+
+			auto fseek_in_usefile = make_check_fseek_func(
+			        "BOOT", "cartridge", temp_line.c_str());
+
 			if (!cart_cmd.empty()) {
 				if (!usefile_1) {
 					WriteOut(MSG_Get("PROGRAM_BOOT_IMAGE_NOT_OPEN"), temp_line.c_str());
 					return;
 				}
 				/* read cartridge data into buffer */
 				constexpr auto seek_pos = 0x200;
-				if (fseek(usefile_1, seek_pos, SEEK_SET) != 0) {
-					LOG_ERR("BOOT: Failed seeking to %d in cartridge data file '%s': %s",
-					        seek_pos, temp_line.c_str(), strerror(errno));
+				if (!fseek_in_usefile(usefile_1, seek_pos, SEEK_SET)) {
 					return;
 				}
 				const auto rom_bytes_expected = rombytesize_1 - 0x200;
@@ -374,9 +387,14 @@ void BOOT::Run(void)
 				return;
 
 			uint32_t sz1, sz2;
-			FILE *tfile = getFSFile("system.rom", &sz1, &sz2, true);
+			constexpr auto rom_filename = "system.rom";
+			FILE* tfile = getFSFile(rom_filename, &sz1, &sz2, true);
 			if (tfile != nullptr) {
-				fseek(tfile, 0x3000L, SEEK_SET);
+				auto fseek_in_rom = make_check_fseek_func(
+				        "BOOT", "system ROM", rom_filename);
+				if (!fseek_in_rom(tfile, 0x3000L, SEEK_SET)) {
+					return;
+				}
 				uint32_t drd = (uint32_t)fread(rombuf, 1, 0xb000, tfile);
 				if (drd == 0xb000) {
 					for (i = 0; i < 0xb000; i++)
@@ -386,7 +404,9 @@ void BOOT::Run(void)
 			}
 
 			if (usefile_2 != nullptr) {
-				fseek(usefile_2, 0x0L, SEEK_SET);
+				if (!fseek_in_usefile(usefile_2, 0x0L, SEEK_SET)) {
+					return;
+				}
 				if (fread(rombuf, 1, 0x200, usefile_2) < 0x200) {
 					LOG_MSG("Failed to read sufficient ROM data");
 					fclose(usefile_2);
@@ -396,9 +416,11 @@ void BOOT::Run(void)
 				PhysPt romseg_pt = host_readw(&rombuf[0x1ce]) << 4;
 
 				/* read cartridge data into buffer */
-				fseek(usefile_2, 0x200L, SEEK_SET);
-				if (fread(rombuf, 1, rombytesize_2 - 0x200,
-				          usefile_2) < rombytesize_2 - 0x200) {
+				if (!fseek_in_usefile(usefile_2, 0x200L, SEEK_SET)) {
+					return;
+				}
+				if (fread(rombuf, 1, rombytesize_2 - 0x200, usefile_2) <
+				    rombytesize_2 - 0x200) {
 					LOG_MSG("Failed to read sufficient ROM data");
 					fclose(usefile_2);
 					return;
@@ -413,7 +435,9 @@ void BOOT::Run(void)
 					phys_writeb(romseg_pt + i, rombuf[i]);
 			}
 
-			fseek(usefile_1, 0x0L, SEEK_SET);
+			if (!fseek_in_usefile(usefile_1, 0x0L, SEEK_SET)) {
+				return;
+			}
 			if (fread(rombuf, 1, 0x200, usefile_1) < 0x200) {
 				LOG_MSG("Failed to read sufficient cartridge data");
 				fclose(usefile_1);
@@ -423,7 +447,9 @@ void BOOT::Run(void)
 			uint16_t romseg = host_readw(&rombuf[0x1ce]);
 
 			/* read cartridge data into buffer */
-			fseek(usefile_1, 0x200L, SEEK_SET);
+			if (!fseek_in_usefile(usefile_1, 0x200L, SEEK_SET)) {
+				return;
+			}
 			if (fread(rombuf, 1, rombytesize_1 - 0x200, usefile_1) <
 			    rombytesize_1 - 0x200) {
 				LOG_MSG("Failed to read sufficient cartridge data");