Commit 2697dd8ae721 for kernel

commit 2697dd8ae721db4f6a53d4f4cbd438212a80f8dc
Author: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Date:   Fri Mar 27 17:31:04 2026 +0000

    mm/mseal: update VMA end correctly on merge

    Previously we stored the end of the current VMA in curr_end, and then upon
    iterating to the next VMA updated curr_start to curr_end to advance to the
    next VMA.

    However, this doesn't take into account the fact that a VMA might be
    updated due to a merge by vma_modify_flags(), which can result in curr_end
    being stale and thus, upon setting curr_start to curr_end, ending up with
    an incorrect curr_start on the next iteration.

    Resolve the issue by setting curr_end to vma->vm_end unconditionally to
    ensure this value remains updated should this occur.

    While we're here, eliminate this entire class of bug by simply setting
    const curr_[start/end] to be clamped to the input range and VMAs, which
    also happens to simplify the logic.

    Link: https://lkml.kernel.org/r/20260327173104.322405-1-ljs@kernel.org
    Fixes: 6c2da14ae1e0 ("mm/mseal: rework mseal apply logic")
    Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
    Reported-by: Antonius <antonius@bluedragonsec.com>
    Closes: https://lore.kernel.org/linux-mm/CAK8a0jwWGj9-SgFk0yKFh7i8jMkwKm5b0ao9=kmXWjO54veX2g@mail.gmail.com/
    Suggested-by: David Hildenbrand (ARM) <david@kernel.org>
    Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
    Reviewed-by: Pedro Falcato <pfalcato@suse.de>
    Acked-by: David Hildenbrand (Arm) <david@kernel.org>
    Cc: Jann Horn <jannh@google.com>
    Cc: Jeff Xu <jeffxu@chromium.org>
    Cc: Liam Howlett <liam.howlett@oracle.com>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mseal.c b/mm/mseal.c
index 316b5e1dec78..ac58643181f7 100644
--- a/mm/mseal.c
+++ b/mm/mseal.c
@@ -56,7 +56,6 @@ static int mseal_apply(struct mm_struct *mm,
 		unsigned long start, unsigned long end)
 {
 	struct vm_area_struct *vma, *prev;
-	unsigned long curr_start = start;
 	VMA_ITERATOR(vmi, mm, start);

 	/* We know there are no gaps so this will be non-NULL. */
@@ -66,6 +65,7 @@ static int mseal_apply(struct mm_struct *mm,
 		prev = vma;

 	for_each_vma_range(vmi, vma, end) {
+		const unsigned long curr_start = MAX(vma->vm_start, start);
 		const unsigned long curr_end = MIN(vma->vm_end, end);

 		if (!(vma->vm_flags & VM_SEALED)) {
@@ -79,7 +79,6 @@ static int mseal_apply(struct mm_struct *mm,
 		}

 		prev = vma;
-		curr_start = curr_end;
 	}

 	return 0;