mprotect fails with Out of Memory

While trying to get my haskell executable to run, I've run into the following peculiar situation:

[51044:41097578] mmap(addr: 0x0000000000000000 [host: 0x0000000000000000], len: 0x16000, prot: 0, flags: 34, fd: -1, offset: 0x0): ret = 0xc0793000
[51044:41097578] mprotect(addr: 0x00000000c0794000 [host: 0x000000010efa1000], len: 0x15000, prot: 3): ret = 0xfffffffffffffff4[LINUX_ENOMEM]
[51044:41097578] munmap(gaddr: 0x00000000c0793000 [host: 0x000000010efa0000], size: 0x16000): ret = 0x0

This seems like it's a valid mprotect call to a mmaped region that was just returned with an offset of 0x1000.

However we fail with bfe00000 != c0794000 + 15000 in L261:

noah/src/mm/mmap.c

Lines 251 to 266 in b61c85c

    
           while (region->gaddr + region->size <= end) { 
        
             hv_vm_protect(region->gaddr, region->size, hvprot); 
        
             mprotect(region->haddr, region->size, prot); 
        
             region->prot = hvprot; 
        
             if (region->list.next == &proc.mm->mm_regions) { 
        
               ret = -LINUX_ENOMEM; 
        
               goto out; 
        
             } 
        
             struct mm_region *next = list_entry(region->list.next, struct mm_region, list); 
        
             if (next->gaddr != region->gaddr + region->size) { 
        
               ret = -LINUX_ENOMEM; 
        
               goto out; 
        
             } 
        
             region = next; 
        
           }

I forked https://github.com/johnothwolo/noah and reproduce this issue using test/testing_root/usr/bin/file. I don't know if this has regressed or if it ever worked, but it looks like this repo is dead and you have more luck with John's fork.

Could you link the program you were trying to run?

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`mprotect` fails with Out of Memory #82

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	while (region->gaddr + region->size <= end) {
	hv_vm_protect(region->gaddr, region->size, hvprot);
	mprotect(region->haddr, region->size, prot);
	region->prot = hvprot;

	if (region->list.next == &proc.mm->mm_regions) {
	ret = -LINUX_ENOMEM;
	goto out;
	}
	struct mm_region *next = list_entry(region->list.next, struct mm_region, list);
	if (next->gaddr != region->gaddr + region->size) {
	ret = -LINUX_ENOMEM;
	goto out;
	}
	region = next;
	}

mprotect fails with Out of Memory #82

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tommythorn commented on Jun 6, 2020

johnothwolo commented on Jun 9, 2020

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`mprotect` fails with Out of Memory #82