sched: fix null pointer access in user space stack (#20)

lux-operating-system · Sep 5, 2024 · 6b934bd · 6b934bd
1 parent 3801406
commit 6b934bd
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Showing 2 changed files with 12 additions and 4 deletions.
diff --git a/src/platform/x86_64/sched/context.c b/src/platform/x86_64/sched/context.c
@@ -138,18 +138,17 @@ int platformSetContext(Thread *t, uintptr_t entry, uintptr_t highest, const char
     while(base % PAGE_SIZE) {
         base++;
     }
-    uintptr_t limit = base + PAGE_SIZE + PLATFORM_THREAD_STACK;
     size_t pages = (PLATFORM_THREAD_STACK+PAGE_SIZE-1)/PAGE_SIZE;
     pages++;
 
-    uintptr_t stack = vmmAllocate(base, limit, pages, VMM_WRITE | VMM_USER);
+    uintptr_t stack = vmmAllocate(base, USER_LIMIT_ADDRESS, pages, VMM_WRITE | VMM_USER);
     if(!stack) return -1;
     memset((void *)stack, 0, PLATFORM_THREAD_STACK + PAGE_SIZE);
 
     stack += PLATFORM_THREAD_STACK;
     ctx->regs.rsp = stack;
 
-    t->highest = stack;     // requisite to sbrk() someday
+    t->highest = stack + PAGE_SIZE;     // requisite to sbrk() someday
     return 0;
 }
 

diff --git a/src/sched/exec.c b/src/sched/exec.c
@@ -82,7 +82,16 @@ pid_t execveMemory(const void *ptr, const char **argv, const char **envp) {
     uint64_t highest;
     uint64_t entry = loadELF(ptr, &highest);
 
-    platformSetContext(process->threads[0], entry, highest, argv, envp);
+    if(platformSetContext(process->threads[0], entry, highest, argv, envp)) {
+        threadUseContext(getTid());
+        free(process->threads[0]->context);
+        free(process->threads[0]);
+        free(process->threads);
+        free(process);
+        setScheduling(true);
+        schedRelease();
+        return 0;
+    }
 
     KDEBUG("created new process with pid %d\n", pid);