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Thu, 09 Oct 2025 02:46:09 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Thu, 9 Oct 2025 11:46:08 +0200 To: Yadong Qi Cc: akpm@linux-foundation.org, urezki@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ying.huang@linux.alibaba.com Subject: Re: [PATCH v3] mm: vmalloc: WARN_ON if mapping size is not PAGE_SIZE aligned Message-ID: References: <20251009093707.868-1-yadong.qi@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251009093707.868-1-yadong.qi@linux.alibaba.com> On Thu, Oct 09, 2025 at 05:37:06PM +0800, Yadong Qi wrote: > In mm/vmalloc.c, the function vmap_pte_range() assumes that the > mapping size is aligned to PAGE_SIZE. If this assumption is > violated, the loop will become infinite because the termination > condition (`addr != end`) will never be met. This can lead to > overwriting other VA ranges and/or random pages physically follow > the page table. > > It's the caller's responsibility to ensure that the mapping size > is aligned to PAGE_SIZE. However, the memory corruption is hard > to root cause. To identify the programming error in the caller > easier, check whether the mapping size is PAGE_SIZE aligned with > WARN_ON(). > > Signed-off-by: Yadong Qi > Reviewed-by: Huang Ying > --- > v2 -> v3: > * change error code from ENOMEM to EINVAL > * modify callers of vmap_pte_range to handle return code > v1 -> v2: > * Use WARN_ON instead of BUG_ON > --- > mm/vmalloc.c | 29 ++++++++++++++++++----------- > 1 file changed, 18 insertions(+), 11 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 5edd536ba9d2..1fa52f203795 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -100,6 +100,9 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, > struct page *page; > unsigned long size = PAGE_SIZE; > > + if (WARN_ON(!PAGE_ALIGNED(end - addr))) > And it might be worth to use WARN_ON_ONCE() otherwise there is a risk that a kernel buffer would contain only such warnings. -- Uladzislau Rezki