linux-kernel - [PATCH] mmap: Fix copy

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Date:   Tue, 11 Oct 2022 20:36:51 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
CC:     Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Liam Howlett <liam.howlett@...cle.com>
Subject: [PATCH] mmap: Fix copy_vma() failure path

The anon vma was not unlinked and the file was not closed in the failure
path when the machine runs out of memory during the maple tree
modification.  This caused a memory leak of the anon vma chain and vma
since neither would be freed.

Reported-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
Fixes: 524e00b36e8c (mm: remove rb tree.)
Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 mm/mmap.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/mmap.c b/mm/mmap.c
index 74c0e3784500..5855f26639f9 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3234,6 +3234,11 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 out_vma_link:
 	if (new_vma->vm_ops && new_vma->vm_ops->close)
 		new_vma->vm_ops->close(new_vma);
+
+	if (new_vma->vm_file)
+		fput(new_vma->vm_file);
+
+	unlink_anon_vmas(new_vma);
 out_free_mempol:
 	mpol_put(vma_policy(new_vma));
 out_free_vma:
-- 
2.35.1