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don't use COW pages in private anonymous mapping (quick fix)

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NAKAMURA Gou
2014-10-17 22:33:13 +09:00
parent 6cd1016d57
commit f195b9c675
1 changed files with 27 additions and 0 deletions
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27
kernel/process.c
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@ -1349,6 +1349,33 @@ static int do_page_fault_process(struct process *proc, void *fault_addr0, uint64
goto out;
}
/*
* XXX: quick fix
* Corrupt data was read by the following sequence.
* 1) a process did mmap(MAP_PRIVATE|MAP_ANONYMOUS)
* 2) the process fetched the contents of a page of (1)'s mapping.
* 3) the process wrote the contents of the page of (1)'s mapping.
* 4) the process changed the contents of the page of (1)'s mapping.
* 5) the process read something in the page of (1)'s mapping.
*
* In the case of the above sequence,
* copy-on-write pages was mapped at (2). And their physical pages
* were informed to mcctrl/mcexec at (3). However, page remapping
* at (4) was not informed to mcctrl/mcexec, and the data read at (5)
* was transferred to old pages which had been mapped at (2).
*/
if ((range->flag & VR_PRIVATE) && range->memobj) {
struct memobj *obj;
if (zeroobj_create(&obj)) {
panic("DPFP: zeroobj_crate");
}
if (range->memobj == obj) {
reason |= PF_POPULATE;
}
}
error = page_fault_process_memory_range(vm, range, fault_addr, reason);
if (error == -ERESTART) {
goto out;