Commit e39a4b33 authored Apr 06, 2020 by Li Xinhai Committed by Linus Torvalds Apr 07, 2020

mm: set vm_next and vm_prev to NULL in vm_area_dup()



Set ->vm_next and ->vm_prev to NULL to prevent potential misuse from the
new duplicated vma.

Currently, only in fork path there are misuse for handling anon_vma.  No
other bugs been revealed with this patch applied.

Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Link: http://lkml.kernel.org/r/1581150928-3214-4-git-send-email-lixinhai.lxh@gmail.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 23ab76bf

kernel/fork.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -361,6 +361,7 @@ struct vm_area_struct vm_area_dup(struct vm_area_struct orig)
		if (new) {
		new = orig;
		INIT_LIST_HEAD(&new->anon_vma_chain);
		new->vm_next = new->vm_prev = NULL;
		}
		return new;
		}
		@@ -562,7 +563,6 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
		} else if (anon_vma_fork(tmp, mpnt))
		goto fail_nomem_anon_vma_fork;
		tmp->vm_flags &= ~(VM_LOCKED \| VM_LOCKONFAULT);
		tmp->vm_next = tmp->vm_prev = NULL;
		file = tmp->vm_file;
		if (file) {
		struct inode *inode = file_inode(file);

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