Imperial-MEng/pintos_22
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Only check user pages rather than all bytes in-between, for known-size pointers

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Gleb Koval
2024-11-12 15:48:22 +00:00
parent cf4bf90cbb
commit 59e7a64f8e
1 changed files with 3 additions and 1 deletions
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4
src/userprog/syscall.c
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@@ -421,7 +421,8 @@ validate_user_pointer (const void *ptr, size_t size, bool check_write)
void *last = ptr + size - 1; void *last = ptr + size - 1;
if (!is_user_vaddr (last)) if (!is_user_vaddr (last))
thread_exit (); thread_exit ();
for (; ptr <= last; ptr++) ptr = pg_round_down (ptr);
while (ptr <= last)
{ {
int result; int result;
/* Check read access to pointer. */ /* Check read access to pointer. */
@@ -430,6 +431,7 @@ validate_user_pointer (const void *ptr, size_t size, bool check_write)
/* Check write access to pointer (if required). */ /* Check write access to pointer (if required). */
if (check_write && !put_user (ptr, result)) if (check_write && !put_user (ptr, result))
thread_exit (); thread_exit ();
ptr += PGSIZE;
} }
} }