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mldr: Unmap reservation before mapping in actual contents
This is necessary as a result of the changes from 0e552ab5454c6c45005f0e8abfa34323c6025d3a.
We do want to make sure we don't replace any previous memory we didn't
load ourselves, so in order to keep that, we just unmap the memory we reserve,
since there's no race condition like there could have been when we were
doing this in the LKM. No one else can be allocating memory in our
process but us.
+9
-1
+9
-1
src/startup/mldr/loader.c
+9
-1
src/startup/mldr/loader.c
···
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exit(1);
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}
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+
// unmap it so we can map the actual segments later using MAP_FIXED_NOREPLACE;
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// we're the only thread running, so there's no chance this memory range will become occupied from now until then
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munmap((void*)slide, mmapSize);
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+
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if (slide + mmapSize > lr->vm_addr_max)
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lr->vm_addr_max = lr->base = slide + mmapSize;
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slide -= base;
···
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if (seg->filesize > 0)
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{
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unsigned long addr = seg->vmaddr + slide;
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int flag = MAP_FIXED_NOREPLACE;
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if (seg->filesize < seg->vmsize) {
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flag = MAP_FIXED;
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}
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rv = mmap((void*)addr, seg->filesize, useprot,
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MAP_FIXED_NOREPLACE | MAP_PRIVATE, fd, seg->fileoff + fat_offset);
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flag | MAP_PRIVATE, fd, seg->fileoff + fat_offset);
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if (rv == (void*)MAP_FAILED)
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{
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fprintf(stderr, "Cannot mmap segment %s at %p: %s\n", seg->segname, (void*)(uintptr_t)seg->vmaddr, strerror(errno));