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Commit 9314dca9 authored by Andrey Ryabinin's avatar Andrey Ryabinin Committed by Susheel Khiani
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mm: rmap: fix use-after-free in __put_anon_vma 



commit 624483f3ea82598ab0f62f1bdb9177f531ab1892 upstream.

While working address sanitizer for kernel I've discovered
use-after-free bug in __put_anon_vma.

For the last anon_vma, anon_vma->root freed before child anon_vma.
Later in anon_vma_free(anon_vma) we are referencing to already freed
anon_vma->root to check rwsem.

This fixes it by freeing the child anon_vma before freeing
anon_vma->root.

Change-Id: Id30e912036bcbe47bafbcd714694c53fdcac60b7
Signed-off-by: default avatarAndrey Ryabinin <a.ryabinin@samsung.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: 65375ce7
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git


Signed-off-by: default avatarSusheel Khiani <skhiani@codeaurora.org>
parent 763e35c9

mm/rmap.c

+1 −2
Original line number Diff line number Diff line
@@ -1675,10 +1675,9 @@ void __put_anon_vma(struct anon_vma *anon_vma) 
{

	struct anon_vma *root = anon_vma->root;



	anon_vma_free(anon_vma);

	if (root != anon_vma && atomic_dec_and_test(&root->refcount))

		anon_vma_free(root);



	anon_vma_free(anon_vma);

}



#ifdef CONFIG_MIGRATION