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[86.156.84.164]) by smtp.gmail.com with ESMTPSA id p24-20020a1c7418000000b003f42456c490sm2047711wmc.33.2023.05.17.04.54.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 May 2023 04:54:00 -0700 (PDT) Date: Wed, 17 May 2023 12:54:00 +0100 From: Lorenzo Stoakes To: Dan Carpenter Cc: linux-mm@kvack.org Subject: Re: [bug report] mm/gup: remove vmas parameter from get_user_pages_remote() Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 61opj5km5wx6p73dnc53hk1k8rsxee3u X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: EAFA2C000C X-HE-Tag: 1684324443-395076 X-HE-Meta: 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 XCcVLdKb ifT9DQDCfdSYgwpShu5G4WMTsGCbHgvZGp7rTB/sLkSR1xK3gTArEl2FqJnLjMBnoyhEv6eWBbR/tpmkaX+PCQm0tvR4FL4sAtI35/w0Eud5Uz4lgeNEhqSBAY75UtpeAxo8tQEmR5spY7sbw33wc8OgK+Zn+58u1vG/a6EXAYdEOfTGB9UAyvtIvUWyIQY10KU/0utyQlNnGUhneb/zlr2MMSZtKMwYPP/wnTKu1HsLizL9dpS8ZipIvsYyNHxnzgnJYG+ns2O0xQxbQ1iVkVRmlybms4iJsU7pbFls2tIj7WA6mI/l6VJCO0S+jncdkEtopa6EbEVNJDH4r8WRpZ6G9KLB0OzssaFq78OCzLjLQGWARgxaXqKTC6kV/rYi1B+VNvy6cJMvprVFVAG7tS9JYSvZ5t0TGlTYvlZNFD8NxTz9Mr1z2lD+GvQ== 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 Wed, May 17, 2023 at 02:45:22PM +0300, Dan Carpenter wrote: > Hello Lorenzo Stoakes, > > The patch eca1a00155df: "mm/gup: remove vmas parameter from > get_user_pages_remote()" from May 14, 2023, leads to the following > Smatch static checker warning: > > mm/memory.c:5617 __access_remote_vm() > error: uninitialized symbol 'vma'. > > mm/memory.c > 5590 int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, > 5591 int len, unsigned int gup_flags) > 5592 { > 5593 void *old_buf = buf; > 5594 int write = gup_flags & FOLL_WRITE; > 5595 > 5596 if (mmap_read_lock_killable(mm)) > 5597 return 0; > 5598 > 5599 /* ignore errors, just check how much was successfully transferred */ > 5600 while (len) { > 5601 int bytes, offset; > 5602 void *maddr; > 5603 struct vm_area_struct *vma; > 5604 struct page *page = get_user_page_vma_remote(mm, addr, > 5605 gup_flags, &vma); > 5606 > 5607 if (IS_ERR_OR_NULL(page)) { > > If page is either an error pointer or NULL then > > 5608 int ret = 0; > 5609 > 5610 #ifndef CONFIG_HAVE_IOREMAP_PROT > 5611 break; > 5612 #else > 5613 /* > 5614 * Check if this is a VM_IO | VM_PFNMAP VMA, which > 5615 * we can access using slightly different code. > 5616 */ > --> 5617 if (!vma) > > that means vma is unitialized. > Ack yeah you're right, this is a product of carrying over the code with a wrapper that behaves slightly differently. I'll fix this + roll in the -fix patch stuff in a new respin tonight. > 5618 break; > 5619 if (vma->vm_ops && vma->vm_ops->access) > 5620 ret = vma->vm_ops->access(vma, addr, buf, > 5621 len, write); > 5622 if (ret <= 0) > 5623 break; > 5624 bytes = ret; > 5625 #endif > 5626 } else { > 5627 bytes = len; > 5628 offset = addr & (PAGE_SIZE-1); > 5629 if (bytes > PAGE_SIZE-offset) > 5630 bytes = PAGE_SIZE-offset; > 5631 > 5632 maddr = kmap(page); > 5633 if (write) { > 5634 copy_to_user_page(vma, page, addr, > 5635 maddr + offset, buf, bytes); > 5636 set_page_dirty_lock(page); > 5637 } else { > 5638 copy_from_user_page(vma, page, addr, > 5639 buf, maddr + offset, bytes); > 5640 } > 5641 kunmap(page); > 5642 put_page(page); > 5643 } > 5644 len -= bytes; > 5645 buf += bytes; > 5646 addr += bytes; > 5647 } > 5648 mmap_read_unlock(mm); > 5649 > 5650 return buf - old_buf; > 5651 } > > regards, > dan carpenter >