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Subject[PATCH v2 1/5] mremap: don't leak new_vma if f_op->mremap() fails
move_vma() can't just return if f_op->mremap() fails, we should
unmap the new vma like we do if move_page_tables() fails. To avoid
the code duplication this patch moves the "move entries back" under
the new "if (err)" branch.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
---
mm/mremap.c | 16 +++++++---------
1 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index a7c93ec..f54a43f 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -276,6 +276,12 @@ static unsigned long move_vma(struct vm_area_struct *vma,
moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
need_rmap_locks);
if (moved_len < old_len) {
+ err = -ENOMEM;
+ } else if (vma->vm_file && vma->vm_file->f_op->mremap) {
+ err = vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
+ }
+
+ if (unlikely(err)) {
/*
* On error, move entries back from new area to old,
* which will succeed since page tables still there,
@@ -286,16 +292,8 @@ static unsigned long move_vma(struct vm_area_struct *vma,
vma = new_vma;
old_len = new_len;
old_addr = new_addr;
- new_addr = -ENOMEM;
+ new_addr = err;
} else {
- if (vma->vm_file && vma->vm_file->f_op->mremap) {
- err = vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
- if (err < 0) {
- move_page_tables(new_vma, new_addr, vma,
- old_addr, moved_len, true);
- return err;
- }
- }
arch_remap(mm, old_addr, old_addr + old_len,
new_addr, new_addr + new_len);
}
--
1.5.5.1


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