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| author | Robert Morris <[email protected]> | 2022-10-04 11:52:57 -0400 |
|---|---|---|
| committer | Robert Morris <[email protected]> | 2022-10-04 11:52:57 -0400 |
| commit | d2b2dff7490f2c4b8e91f79940fc46f0361c216c (patch) | |
| tree | 2db70a0e68469411a5b2cb007e8ec65f67790439 /kernel/vm.c | |
| parent | 989e8f2f1f5bd68731472874bed19fab48a202af (diff) | |
| download | xv6-labs-d2b2dff7490f2c4b8e91f79940fc46f0361c216c.tar.gz xv6-labs-d2b2dff7490f2c4b8e91f79940fc46f0361c216c.tar.bz2 xv6-labs-d2b2dff7490f2c4b8e91f79940fc46f0361c216c.zip | |
fix copyout() to refuse to write a read-only page
Diffstat (limited to 'kernel/vm.c')
| -rw-r--r-- | kernel/vm.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/vm.c b/kernel/vm.c index 9f69783..486945e 100644 --- a/kernel/vm.c +++ b/kernel/vm.c @@ -352,12 +352,17 @@ int copyout(pagetable_t pagetable, uint64 dstva, char *src, uint64 len) { uint64 n, va0, pa0; + pte_t *pte; while(len > 0){ va0 = PGROUNDDOWN(dstva); - pa0 = walkaddr(pagetable, va0); - if(pa0 == 0) + if(va0 >= MAXVA) + return -1; + pte = walk(pagetable, va0, 0); + if(pte == 0 || (*pte & PTE_V) == 0 || (*pte & PTE_U) == 0 || + (*pte & PTE_W) == 0) return -1; + pa0 = PTE2PA(*pte); n = PGSIZE - (dstva - va0); if(n > len) n = len; |