[merged mm-hotfixes-stable] mm-mremap-fix-regression-in-vrm-new_addr-check.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The quilt patch titled
     Subject: mm/mremap: fix regression in vrm->new_addr check
has been removed from the -mm tree.  Its filename was
     mm-mremap-fix-regression-in-vrm-new_addr-check.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Carlos Llamas <cmllamas@google.com>
Subject: mm/mremap: fix regression in vrm->new_addr check
Date: Thu, 28 Aug 2025 14:26:56 +0000

Commit 3215eaceca87 ("mm/mremap: refactor initial parameter sanity
checks") moved the sanity check for vrm->new_addr from mremap_to() to
check_mremap_params().

However, this caused a regression as vrm->new_addr is now checked even
when MREMAP_FIXED and MREMAP_DONTUNMAP flags are not specified.  In this
case, vrm->new_addr can be garbage and create unexpected failures.

Fix this by moving the new_addr check after the vrm_implies_new_addr()
guard.  This ensures that the new_addr is only checked when the user has
specified one explicitly.

Link: https://lkml.kernel.org/r/20250828142657.770502-1-cmllamas@google.com
Fixes: 3215eaceca87 ("mm/mremap: refactor initial parameter sanity checks")
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Carlos Llamas <cmllamas@google.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mremap.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/mm/mremap.c~mm-mremap-fix-regression-in-vrm-new_addr-check
+++ a/mm/mremap.c
@@ -1774,15 +1774,18 @@ static unsigned long check_mremap_params
 	if (!vrm->new_len)
 		return -EINVAL;
 
-	/* Is the new length or address silly? */
-	if (vrm->new_len > TASK_SIZE ||
-	    vrm->new_addr > TASK_SIZE - vrm->new_len)
+	/* Is the new length silly? */
+	if (vrm->new_len > TASK_SIZE)
 		return -EINVAL;
 
 	/* Remainder of checks are for cases with specific new_addr. */
 	if (!vrm_implies_new_addr(vrm))
 		return 0;
 
+	/* Is the new address silly? */
+	if (vrm->new_addr > TASK_SIZE - vrm->new_len)
+		return -EINVAL;
+
 	/* The new address must be page-aligned. */
 	if (offset_in_page(vrm->new_addr))
 		return -EINVAL;
_

Patches currently in -mm which might be from cmllamas@google.com are