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Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , Jeff Xu , David Hildenbrand , linux-mm@kvack.org, linux-kernel@vger.kernel.org, antonius Subject: [PATCH v2] mm/mseal: update VMA end correctly on merge Date: Fri, 27 Mar 2026 17:31:04 +0000 Message-ID: <20260327173104.322405-1-ljs@kernel.org> X-Mailer: git-send-email 2.53.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Stat-Signature: djenytwbiuft5szpgwcm46j9aa9d76a3 X-Rspamd-Queue-Id: DE65A4000B X-Rspam-User: X-HE-Tag: 1774632670-872792 X-HE-Meta: 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 M6c6I11Z TSNfOHsKLDzczkcD4H5YSMSFNGytbh8SdWGqQrqi5FRKRWhdjIQ93Gs2NujX7rPZvwabsW2P4WNgon/KioVXD2XYKJu45/wnjsPa0FtC8QWe8zWBbddW/2AzGQxPZe7OpxsBWSSBZ7tXDgcQcuPTFE8mY5tZsTNDQWrBxNetyb/N2IO0xu8zNguih6TyGjAi3Jvws+YKq5rgA6VCg6FK0QXCynkr18noI7EOfJ+GHW7VAEp+sitAqssAPDLwcxYSodMazfanab9Xf1wTdFc3LCymc58i/VmrPrGO1U7fqZQyb2s4ToqVzPYoXIpqrAbd/vcVqf9qbjk5KChgAmkMk+lJsZg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. Reported-by: Antonius Closes: https://lore.kernel.org/linux-mm/CAK8a0jwWGj9-SgFk0yKFh7i8jMkwKm5b0ao9=kmXWjO54veX2g@mail.gmail.com/ Suggested-by: David Hildenbrand (ARM) Acked-by: Vlastimil Babka (SUSE) Reviewed-by: Pedro Falcato Signed-off-by: Lorenzo Stoakes (Oracle) Fixes: 6c2da14ae1e0 ("mm/mseal: rework mseal apply logic") Cc: --- v2: * Correct Closes: tag * Use David's excellent idea to improve the patch v1: https://lore.kernel.org/all/20260327090640.146308-1-ljs@kernel.org/ mm/mseal.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) 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; -- 2.53.0