+ mm-mempolicy-fix-set_mempolicy_home_node-previous-vma-pointer.patch added to mm-hotfixes-unstable branch

+ mm-mempolicy-fix-set_mempolicy_home_node-previous-vma-pointer.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/mempolicy: fix set_mempolicy_home_node() previous VMA pointer
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-mempolicy-fix-set_mempolicy_home_node-previous-vma-pointer.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mempolicy-fix-set_mempolicy_home_node-previous-vma-pointer.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Subject: mm/mempolicy: fix set_mempolicy_home_node() previous VMA pointer
Date: Thu, 28 Sep 2023 13:24:32 -0400

The two users of mbind_range() are expecting that mbind_range() will
update the pointer to the previous VMA, or return an error.  However,
set_mempolicy_home_node() does not call mbind_range() if there is no VMA
policy.  The fix is to update the pointer to the previous VMA prior to
continuing iterating the VMAs when there is no policy.

Users may experience a WARN_ON() during VMA policy updates when updating
a range of VMAs on the home node.

Link: https://lkml.kernel.org/r/20230928172432.2246534-1-Liam.Howlett@oracle.com
Link: https://lore.kernel.org/linux-mm/CALcu4rbT+fMVNaO_F2izaCT+e7jzcAciFkOvk21HGJsmLcUuwQ@mail.gmail.com/
Fixes: f4e9e0e69468 ("mm/mempolicy: fix use-after-free of VMA iterator")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: Yikebaer Aizezi <yikebaer61@gmail.com>
Closes: https://lore.kernel.org/linux-mm/CALcu4rbT+fMVNaO_F2izaCT+e7jzcAciFkOvk21HGJsmLcUuwQ@mail.gmail.com/
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mempolicy.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/mempolicy.c~mm-mempolicy-fix-set_mempolicy_home_node-previous-vma-pointer
+++ a/mm/mempolicy.c
@@ -1543,8 +1543,10 @@ SYSCALL_DEFINE4(set_mempolicy_home_node,
 		 * the home node for vmas we already updated before.
 		 */
 		old = vma_policy(vma);
-		if (!old)
+		if (!old) {
+			prev = vma;
 			continue;
+		}
 		if (old->mode != MPOL_BIND && old->mode != MPOL_PREFERRED_MANY) {
 			err = -EOPNOTSUPP;
 			break;
_

Patches currently in -mm which might be from Liam.Howlett@oracle.com are

maple_tree-add-mas_active-to-detect-in-tree-walks.patch
maple_tree-add-mas_underflow-and-mas_overflow-states.patch
mmap-fix-vma_iterator-in-error-path-of-vma_merge.patch
mmap-fix-error-paths-with-dup_anon_vma.patch
mm-mempolicy-fix-set_mempolicy_home_node-previous-vma-pointer.patch
mmap-add-clarifying-comment-to-vma_merge-code.patch