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Sat, 15 Apr 2023 19:36:07 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Message-ID: <65e79cf8-8713-4d2d-7a50-76d7e2aa454a@I-love.SAKURA.ne.jp> Date: Sat, 15 Apr 2023 19:36:06 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH v2 3/7] mm/gup: remove vmas parameter from get_user_pages_remote() Content-Language: en-US To: Lorenzo Stoakes Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <631001ecc556c5e348ff4f47719334c31f7bd592.1681547405.git.lstoakes@gmail.com> <63d92734-2185-439c-bbc7-53a4720f5d4a@lucifer.local> From: Tetsuo Handa In-Reply-To: <63d92734-2185-439c-bbc7-53a4720f5d4a@lucifer.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 40B4718000A X-Stat-Signature: xy4kohiw9enqhg8fwh1h6fpstiknrxnh X-Rspam-User: X-HE-Tag: 1681554972-141834 X-HE-Meta: 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 +U2PGQka SWjAVPEzcW0rtiFVpwFkL8Xmt+ECrDFO0MNQcQmq/iku322Smgr3qfasWr9AvG8HKQG6SZpcEjgldSTfxRaIbDztJLaE7VLZiSX+A51mzqUGFptzosYMr78YNAGezSanaJdphvX/s8+vSQ/uDjNPP2f/RNmRJG50VVLZMFbiTRJbyUl9mZM+H/TktmFTYQvx7io3Cz04Y1PjgnP3sD5NSUC+0uYoqY1j9FoQSER9y9G5FKizXp3YsRaRi14HcQyYV1hthJYZlGFU+bGQLyG99lhpQnA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2023/04/15 19:14, Lorenzo Stoakes wrote: > On Sat, Apr 15, 2023 at 06:52:41PM +0900, Tetsuo Handa wrote: >> On 2023/04/15 18:08, Lorenzo Stoakes wrote: >>> @@ -475,10 +474,14 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, >>> gup_flags |= FOLL_SPLIT_PMD; >>> /* Read the page with vaddr into memory */ >>> ret = get_user_pages_remote(mm, vaddr, 1, gup_flags, >>> - &old_page, &vma, NULL); >>> + &old_page, NULL); >>> if (ret <= 0) >>> return ret; >>> >>> + vma = vma_lookup(mm, vaddr); >>> + if (!vma) >>> + goto put_old; >>> + >>> ret = verify_opcode(old_page, vaddr, &opcode); >>> if (ret <= 0) >>> goto put_old; >> >> This conversion looks wrong. >> This causes returning a positive number when vma_lookup() returned NULL. >> >> * Return 0 (success) or a negative errno. >> > > In reality it shouldn't be possible for vma to return NULL, I'm adding the > checks to be extra careful. > > In any case you're right, attaching a -fix patch to avoid spam:- If you want to return -EINVAL when vma_lookup() returned NULL for whatever unexpected reason, returning -EOPNOTSUPP in below path looks strange. > @@ -448,7 +448,8 @@ static int __access_remote_tags(struct mm_struct *mm, unsigned long addr, > * would cause the existing tags to be cleared if the page > * was never mapped with PROT_MTE. > */ > - if (!(vma->vm_flags & VM_MTE)) { > + vma = vma_lookup(mm, addr); > + if (!vma || !(vma->vm_flags & VM_MTE)) { > ret = -EOPNOTSUPP; > put_page(page); > break; Also, > @@ -5591,7 +5591,9 @@ int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, > struct page *page = NULL; > > ret = get_user_pages_remote(mm, addr, 1, > - gup_flags, &page, &vma, NULL); > + gup_flags, &page, NULL); > + vma = vma_lookup(mm, addr); > + > if (ret <= 0) { > #ifndef CONFIG_HAVE_IOREMAP_PROT > break; > @@ -5600,7 +5602,6 @@ int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, > * Check if this is a VM_IO | VM_PFNMAP VMA, which > * we can access using slightly different code. > */ > - vma = vma_lookup(mm, addr); > if (!vma) > break; > if (vma->vm_ops && vma->vm_ops->access) > @@ -5617,11 +5618,11 @@ int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, > bytes = PAGE_SIZE-offset; > > maddr = kmap(page); > - if (write) { > + if (write && vma) { > copy_to_user_page(vma, page, addr, > maddr + offset, buf, bytes); > set_page_dirty_lock(page); > - } else { > + } else if (vma) { > copy_from_user_page(vma, page, addr, > buf, maddr + offset, bytes); > } not calling copy_{from,to}_user_page() if vma == NULL is not sufficient for propagating an error to caller.