m68k: call find_vma with the mmap_sem held in sys_cacheflush()
Performing vma lookups without taking the mm->mmap_sem is asking for trouble. While doing the search, the vma in question can be modified or even removed before returning to the caller. Take the lock (shared) in order to avoid races while iterating through the vmacache and/or rbtree. In addition, this guarantees that the address space will remain intact during the CPU flushing. Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -376,7 +376,6 @@ cache_flush_060 (unsigned long addr, int scope, int cache, unsigned long len)
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asmlinkage int
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asmlinkage int
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sys_cacheflush (unsigned long addr, int scope, int cache, unsigned long len)
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sys_cacheflush (unsigned long addr, int scope, int cache, unsigned long len)
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{
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{
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struct vm_area_struct *vma;
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int ret = -EINVAL;
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int ret = -EINVAL;
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if (scope < FLUSH_SCOPE_LINE || scope > FLUSH_SCOPE_ALL ||
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if (scope < FLUSH_SCOPE_LINE || scope > FLUSH_SCOPE_ALL ||
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@ -389,17 +388,21 @@ sys_cacheflush (unsigned long addr, int scope, int cache, unsigned long len)
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if (!capable(CAP_SYS_ADMIN))
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if (!capable(CAP_SYS_ADMIN))
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goto out;
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goto out;
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} else {
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} else {
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struct vm_area_struct *vma;
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/* Check for overflow. */
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if (addr + len < addr)
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goto out;
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/*
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/*
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* Verify that the specified address region actually belongs
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* Verify that the specified address region actually belongs
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* to this process.
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* to this process.
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*/
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*/
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vma = find_vma (current->mm, addr);
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ret = -EINVAL;
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ret = -EINVAL;
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/* Check for overflow. */
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down_read(¤t->mm->mmap_sem);
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if (addr + len < addr)
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vma = find_vma(current->mm, addr);
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goto out;
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if (!vma || addr < vma->vm_start || addr + len > vma->vm_end)
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if (vma == NULL || addr < vma->vm_start || addr + len > vma->vm_end)
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goto out_unlock;
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goto out;
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}
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}
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if (CPU_IS_020_OR_030) {
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if (CPU_IS_020_OR_030) {
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@ -429,7 +432,7 @@ sys_cacheflush (unsigned long addr, int scope, int cache, unsigned long len)
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__asm__ __volatile__ ("movec %0, %%cacr" : : "r" (cacr));
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__asm__ __volatile__ ("movec %0, %%cacr" : : "r" (cacr));
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}
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}
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ret = 0;
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ret = 0;
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goto out;
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goto out_unlock;
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} else {
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} else {
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/*
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/*
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* 040 or 060: don't blindly trust 'scope', someone could
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* 040 or 060: don't blindly trust 'scope', someone could
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@ -446,6 +449,8 @@ sys_cacheflush (unsigned long addr, int scope, int cache, unsigned long len)
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ret = cache_flush_060 (addr, scope, cache, len);
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ret = cache_flush_060 (addr, scope, cache, len);
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}
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}
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}
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}
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out_unlock:
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up_read(¤t->mm->mmap_sem);
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out:
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out:
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return ret;
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return ret;
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}
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}
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