diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/mmu_context.h | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/shstk.c | 22 |
2 files changed, 21 insertions, 4 deletions
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index 416901d406f8..8dac45a2c7fc 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -186,8 +186,7 @@ do { \ #else #define deactivate_mm(tsk, mm) \ do { \ - if (!tsk->vfork_done) \ - shstk_free(tsk); \ + shstk_free(tsk); \ load_gs_index(0); \ loadsegment(fs, 0); \ } while (0) diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c index fd689921a1db..ad63252ebebc 100644 --- a/arch/x86/kernel/shstk.c +++ b/arch/x86/kernel/shstk.c @@ -205,10 +205,21 @@ unsigned long shstk_alloc_thread_stack(struct task_struct *tsk, unsigned long cl return 0; /* - * For CLONE_VM, except vfork, the child needs a separate shadow + * For CLONE_VFORK the child will share the parents shadow stack. + * Make sure to clear the internal tracking of the thread shadow + * stack so the freeing logic run for child knows to leave it alone. + */ + if (clone_flags & CLONE_VFORK) { + shstk->base = 0; + shstk->size = 0; + return 0; + } + + /* + * For !CLONE_VM the child will use a copy of the parents shadow * stack. */ - if ((clone_flags & (CLONE_VFORK | CLONE_VM)) != CLONE_VM) + if (!(clone_flags & CLONE_VM)) return 0; size = adjust_shstk_size(stack_size); @@ -408,6 +419,13 @@ void shstk_free(struct task_struct *tsk) if (!tsk->mm || tsk->mm != current->mm) return; + /* + * If shstk->base is NULL, then this task is not managing its + * own shadow stack (CLONE_VFORK). So skip freeing it. + */ + if (!shstk->base) + return; + unmap_shadow_stack(shstk->base, shstk->size); } |