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a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1676540939; bh=PX8dOl30j3Yr0k0JAknV8dpZqe1VdlzvplpwBLPzdKc=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=H5v4ZpM/z+wrQUpEW5xK3yLSyNMR0XOXYFHJm9aBPg6Ze0M6QB+Yehh9TffL/TsgJ U/WkkBKQ3mZzJpky43EowepFh60QwCIA2bs0+cQOmI9RPBSkUE34dumQbB5gWwh7qK dHzIqN2OS5SPKKquYugbRwUcPJ5UmeKyoZhhxsFWm1z3NBRjio2bREYV36Yj5UUntK BwVsSYglk00vNqe9Nm6tigdcqXGI+8j1OwF8AMu5qOAv8OQiD2EWtYW2fOlxNOa9lt QwFBvfsyxNQX9YdZ55BYpdyO+nO5VRmcU/uiFlVGpBl4WeHTHtdcwvidj2dct8z20U l1amKTZJEEPeg== Message-ID: Date: Thu, 16 Feb 2023 14:48:51 +0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Cc: Muhammad Usama Anjum , kernel@collabora.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 2/2] mm/userfaultfd: add VM_WARN_ONCE() Content-Language: en-US To: David Hildenbrand , peterx@redhat.com, Andrew Morton References: <20230216091656.2045471-1-usama.anjum@collabora.com> <20230216091656.2045471-2-usama.anjum@collabora.com> <4d29a9ec-027d-06b9-8543-87d386e58c94@redhat.com> From: Muhammad Usama Anjum In-Reply-To: <4d29a9ec-027d-06b9-8543-87d386e58c94@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: BE873A0002 X-Rspamd-Server: rspam01 X-Stat-Signature: py7ct5ytp4r584fmejkh58w3on985ztb X-HE-Tag: 1676540940-308026 X-HE-Meta: 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 NdhI+YlZ YMDHnnA1Z0kBY8m4CeGTGJFdu6Y1x0z6BOoZ5FvVFwcxPyG26V1KLyoUAv86k2dkPL1WF/PCs7SyNKTLjP3OuwtSREteRg/8wJe0f6wCrkmtwLfewdf0W5MsfEx32Tz+66B/NY8SztTBtt5SprhiYGpiUvFT1xkw+K5uv7EcJ14oau04tkRgYdEVqemI9Dk1L+T6VrilDvuegxCocOIwvm4/sLYkNrIUaC5Q+dg8Xj6NRMM5EEV3/RZfCU8qUOut18mnb2wUxK+p4bzRY37eTpcjnT0AyGrT/Uw5ffW6qnE7RY+PsVrbliGdVbHluUvcQobz7 X-Bogosity: Ham, tests=bogofilter, spamicity=0.001984, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2/16/23 2:24 PM, David Hildenbrand wrote: > On 16.02.23 10:16, Muhammad Usama Anjum wrote: >> Add VM_WARN_ONCE() to uffd_wp_range() to detect range (start, len) abuse. >> >> Signed-off-by: Muhammad Usama Anjum >> --- >>   mm/userfaultfd.c | 2 ++ >>   1 file changed, 2 insertions(+) >> >> diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c >> index 77c5839e591c..d89ed44d2668 100644 >> --- a/mm/userfaultfd.c >> +++ b/mm/userfaultfd.c >> @@ -717,6 +717,8 @@ long uffd_wp_range(struct mm_struct *dst_mm, struct >> vm_area_struct *dst_vma, >>       struct mmu_gather tlb; >>       long ret; >>   +    VM_WARN_ONCE(start < dst_vma->vm_start || start + len > >> dst_vma->vm_end, >> +             "The address range exceeds VMA boundary.\n"); > > VM_WARN_ON_ONCE is sufficient (sorry for spelling out the wrong variant > earlier). Will do in the next version. Thanks. > > These kinds of bugs are expected to be found early during testing, still it > might make sense to implement a backup path > > if (WARN_ON_ONCE(...)) >     return -EINVAL; > > But we can't use VM_WARN_ON_ONCE here, so we can't compile it out anymore > ... so I guess a simple VM_WARN_ON_ONCE() is sufficient. > -- BR, Muhammad Usama Anjum