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x86: mmu/mem_domain: don't translate address before null check

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When adding a new thread to memory domain, there is a NULL check
to figure out if a thread is being migrated to another memory
domain. However, the NULL check is AFTER physical-to-virtual
address translation which means (NULL + offset) != NULL anymore.
This results in calling reset_region() with an invalid page table
pointer. Fix this by doing the NULL check before address
translation.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This commit is contained in:
Daniel Leung 2021-03-01 11:55:21 -08:00 • committed by Anas Nashif
commit fa6d7cecb5
1 changed files with 6 additions and 2 deletions
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8
arch/x86/core/x86_mmu.c
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@ -1661,9 +1661,12 @@ void arch_mem_domain_thread_add(struct k_thread *thread)
/* New memory domain we are being added to */
struct k_mem_domain *domain = thread->mem_domain_info.mem_domain;
/* This is only set for threads that were migrating from some other
* memory domain; new threads this is NULL
* memory domain; new threads this is NULL.
*
* Note that NULL check on old_ptables must be done before any
* address translation or else (NULL + offset) != NULL.
*/
pentry_t *old_ptables = z_x86_virt_addr(thread->arch.ptables);
pentry_t *old_ptables = UINT_TO_POINTER(thread->arch.ptables);
bool is_user = (thread->base.user_options & K_USER) != 0;
bool is_migration = (old_ptables != NULL) && is_user;
@ -1672,6 +1675,7 @@ void arch_mem_domain_thread_add(struct k_thread *thread)
* z_x86_current_stack_perms()
*/
if (is_migration) {
old_ptables = z_x86_virt_addr(thread->arch.ptables);
set_stack_perms(thread, domain->arch.ptables);
}