Write values directly to a memory address.

Co-authored-by: sigonasr2 <sigonasr2@gmail.com>

C/scripts/build.sh

@@ -2,6 +2,6 @@
 #C
 printf "Running program...\n\n\n"
 if gcc $(find . -type f -name "*.c") ${CUSTOM_PARAMS} -o ${PROJECT_NAME}; then
-    ./${PROJECT_NAME} "$@"
+    sudo ./${PROJECT_NAME} "$@"
 fi
 printf "\n\n"

main.c

@@ -1,17 +1,21 @@
 #include <stdio.h>
-#include <sys/uio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
 
-unsigned long strToLong(char*str) {
+unsigned long long strToLong(char*str) {
     int counter=0;
     char c;
     unsigned long val=0;
     int base=10;
     while ((c=str[counter++])!='\0') {
-        if (counter==1&&c=='0') {
+        if (c=='0'&&val==0&&base==10) {
             base=8;
             continue;
         } else
-        if (counter==2&&c=='x') {
+        if (c=='x'&&val==0&&base==8) {
             base=16;
             continue;
         }
@@ -29,8 +33,8 @@ unsigned long strToLong(char*str) {
 }
 
 int main(int argc,char**argv) {
-    unsigned int pid;
-    unsigned long addr;
+    long unsigned int pid;
+    unsigned long long addr;
     unsigned long val;
     unsigned int interval=1000;
     if (argc<4) {
@@ -44,8 +48,32 @@ int main(int argc,char**argv) {
             interval=strToLong(argv[4]);
         }
         printf("\nPID: %lu",pid);
-            printf("\nAddress: %lu",addr);
+        printf("\nAddress: 0x%08llx",addr);
         printf("\nValue: %lu",val);
-            printf("\nInterval: %lu",interval);
+        printf("\nInterval: %d",interval);
+
+        char*proc_mem = malloc(50);
+        sprintf(proc_mem,"/proc/%ld/mem",pid);
+        int fd_proc_mem=open(proc_mem,O_RDWR);
+        if (fd_proc_mem==-1) {
+            printf("Could not open %s\n",proc_mem);
+            exit(1);
+        }
+        char*buf=malloc(sizeof(unsigned int));
+        lseek(fd_proc_mem,addr,SEEK_SET);
+        read(fd_proc_mem,buf,sizeof(unsigned int));
+        while (1) {
+            sprintf(buf,"%d",(int)val++);
+            lseek(fd_proc_mem,addr,SEEK_SET);
+            if (write(fd_proc_mem,buf,sizeof(unsigned int))==-1) {
+                printf("Error while writing\n");
+                exit(1);
+            }
+            printf("\nWrite %d",(int)val-1);
+            sleep(2);
+        }
+
+        free(buf);
+        free(proc_mem);
     }
 }

sig

@@ -1,4 +1,4 @@
-export AUTO_UPDATE=true
+export AUTO_UPDATE=false
 
 source utils/define.sh
 

testProgram.

@@ -0,0 +1,20 @@
+
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+
+int main() {
+
+  char foo[] = "This is some text from proc-1";
+
+  printf("Now execute\n");
+  printf("  sudo ./testProgram2  %d  %lx  %lu\n", getpid(), (long unsigned int) foo, strlen(foo)+1);
+
+  printf("Press any key\n");
+while (1) {
+  getchar();
+
+  printf("foo has changed to: %s\n", foo);
+}
+
+}

testProgram2.

@@ -0,0 +1,49 @@
+#include <stdio.h>
+#include <stdlib.h>
+// #include <sys/mman.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+
+int main(int argc, char* argv[]) {
+
+  if (argc != 4) {
+    printf("proc-2  pid  addr  length\n");
+    exit(1);
+  }
+
+  int           pid  = strtol (argv[1], NULL, 10);
+  unsigned long addr = strtoul(argv[2], NULL, 16);
+  int           len  = strtol (argv[3], NULL, 10);
+
+  char* proc_mem = malloc(50);
+  sprintf(proc_mem, "/proc/%d/mem", pid);
+
+  printf("opening %s, address is %ld\n", proc_mem, addr);
+  int fd_proc_mem = open(proc_mem, O_RDWR);
+  if (fd_proc_mem == -1) {
+    printf("Could not open %s\n", proc_mem);
+    exit(1);
+  }
+
+  char* buf = malloc(len);
+
+  lseek(fd_proc_mem, addr, SEEK_SET);
+  read (fd_proc_mem, buf , len     );
+
+  printf("String at %ld in process %d is:\n", addr, pid);
+  printf("  %s\n", buf);
+
+  printf("\nNow, this string is modified\n");
+  strncpy(buf, "Hello from proc-2", len);
+
+  lseek(fd_proc_mem, addr, SEEK_SET);
+  if (write (fd_proc_mem, buf , len     ) == -1) {
+     printf("Error while writing\n");
+     exit(1);
+  }
+
+  free(buf);
+  free(proc_mem);
+}