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

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merged 1 commit into from
Sep 5, 2024
Merged

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

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5 changes: 2 additions & 3 deletions src/platform/x86_64/sched/context.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
}

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11 changes: 10 additions & 1 deletion src/sched/exec.c
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Expand Up @@ -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);

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