linux-kernel - [PATCH] mm/mmap: undo ->mmap() when mas

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Date:   Mon, 17 Oct 2022 19:49:45 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Muchun Song <songmuchun@...edance.com>,
        Liam Howlett <liam.howlett@...cle.com>,
        Carlos Llamas <cmllamas@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>
Subject: [PATCH] mm/mmap: undo ->mmap() when mas_preallocate() fails

A memory leak in hugetlb_reserve_pages was reported in [1].  The root
cause was traced to an error path in mmap_region when mas_preallocate()
fails.  In this case, the vma is freed after a successful call to
filesystem specific mmap.  The hugetlbfs mmap routine may allocate data
structures pointed to by m_private_data.  These need to be cleaned up
by the hugetlb vm_ops->close() routine.

The same issue was addressed by commit deb0f6562884 ("mm/mmap: undo
->mmap() when arch_validate_flags() fails") for the arch_validate_flags()
test.  Go to the same close_and_free_vma label if mas_preallocate() fails.

[1] https://lore.kernel.org/linux-mm/CAKXUXMxf7OiCwbxib7MwfR4M1b5+b3cNTU7n5NV9Zm4967=FPQ@mail.gmail.com/

Fixes: d4af56c5c7c6 ("mm: start tracking VMAs with maple tree")
Reported-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>
---
 mm/mmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index bf2122af94e7..3c9890e443a3 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2681,7 +2681,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	if (mas_preallocate(&mas, vma, GFP_KERNEL)) {
 		error = -ENOMEM;
 		if (file)
-			goto unmap_and_free_vma;
+			goto close_and_free_vma;
 		else
 			goto free_vma;
 	}
-- 
2.37.3