[PATCH 4.17 299/324] mm: make vm_area_dup() actually copy the old vma data

Greg Kroah-Hartman
2018-08-23T09:08:51Z

From: Linus Torvalds <torvalds@linux-foundation.org>

[ Upstream commit 95faf6992df468f617edb788da8c21c6eed0dfa7 ]

.. and re-initialize th eanon_vma_chain head.

This removes some boiler-plate from the users, and also makes it clear
why it didn't need use the 'zalloc()' version.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/fork.c | 10 +++++++---
mm/mmap.c | 7 -------
mm/nommu.c | 1 -
3 files changed, 7 insertions(+), 11 deletions(-)

--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -315,7 +315,13 @@ struct vm_area_struct *vm_area_alloc(voi

struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
{
- return kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
+ struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
+
+ if (new) {
+ *new = *orig;
+ INIT_LIST_HEAD(&new->anon_vma_chain);
+ }
+ return new;
}

void vm_area_free(struct vm_area_struct *vma)
@@ -473,8 +479,6 @@ static __latent_entropy int dup_mmap(str
tmp = vm_area_dup(mpnt);
if (!tmp)
goto fail_nomem;
- *tmp = *mpnt;
- INIT_LIST_HEAD(&tmp->anon_vma_chain);
retval = vma_dup_policy(mpnt, tmp);
if (retval)
goto fail_nomem_policy;
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2624,11 +2624,6 @@ int __split_vma(struct mm_struct *mm, st
if (!new)
return -ENOMEM;

- /* most fields are the same, copy all, and then fixup */
- *new = *vma;
-
- INIT_LIST_HEAD(&new->anon_vma_chain);
-
if (new_below)
new->vm_end = addr;
else {
@@ -3205,13 +3200,11 @@ struct vm_area_struct *copy_vma(struct v
new_vma = vm_area_dup(vma);
if (!new_vma)
goto out;
- *new_vma = *vma;
new_vma->vm_start = addr;
new_vma->vm_end = addr + len;
new_vma->vm_pgoff = pgoff;
if (vma_dup_policy(vma, new_vma))
goto out_free_vma;
- INIT_LIST_HEAD(&new_vma->anon_vma_chain);
if (anon_vma_clone(new_vma, vma))
goto out_free_mempol;
if (new_vma->vm_file)
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1476,7 +1476,6 @@ int split_vma(struct mm_struct *mm, stru
}

/* most fields are the same, copy all, and then fixup */
- *new = *vma;
*region = *vma->vm_region;
new->vm_region = region;