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Sat, 25 Nov 2023 10:58:02 -0500 X-MC-Unique: PcsJqFGmNXWiUc_k0Z90Xg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CD59A1C04B4C; Sat, 25 Nov 2023 15:58:01 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.14]) by smtp.corp.redhat.com (Postfix) with SMTP id AE6B35028; Sat, 25 Nov 2023 15:57:57 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Sat, 25 Nov 2023 16:56:56 +0100 (CET) Date: Sat, 25 Nov 2023 16:56:51 +0100 From: Oleg Nesterov To: Rong Tao Cc: Andrew Morton , Catalin Marinas , Florent Revest , Kees Cook , David Hildenbrand , Stefan Roesch , Andy Chiu , Josh Triplett , Joey Gouly , Miguel Ojeda , Ondrej Mosnacek , "open list:MEMORY MANAGEMENT" , open list , rongtao@cestc.cn Subject: Re: [PATCH] prctl: Get private anonymous memory region name Message-ID: <20231125155651.GA23245@redhat.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A59FD40009 X-Stat-Signature: 9o695gcfr8gapn7i8oegukyjjarrxnd4 X-Rspam-User: X-HE-Tag: 1700927887-891083 X-HE-Meta: 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 NmDIkSLF EQj1rB/x8zmFd4U1Xw4GmXcL2oVM2y8Xafsm4JawcDGdc2YzcpOIvc95hwODrZwSwK6zDW2MUdAv++J95jJnPlTTBMn1iOajjLCPVWWZIz2XYCQtuVlBvD79e7gaIDyJD0Ned59Qq9vHPxeVmc0MN0+Nz4d/QD/JJzicBGJ6aydBwKUKFfUipAZmMfFgdAeeh7PMg 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: List-Subscribe: List-Unsubscribe: On 11/25, Rong Tao wrote: > > +static int prctl_get_vma(unsigned long opt, unsigned long addr, > + unsigned long buf, unsigned long arg) > +{ > + struct mm_struct *mm = current->mm; > + const char __user *u_buf; > + int error; > + > + switch (opt) { > + case PR_GET_VMA_ANON_NAME: > + const struct anon_vma_name *anon_name = NULL; > + > + u_buf = (const char __user *)buf; > + error = 0; > + > + mmap_read_lock(mm); > + anon_name = madvise_get_anon_name(mm, addr); > + if (!anon_name) { > + mmap_read_unlock(mm); > + error = -EFAULT; may be another error code makes sense to distinguish this case from the copy_to_user() failure? > + break; > + } > + > + if (copy_to_user((char __user *)u_buf, anon_name->name, > + strlen(anon_name->name) + 1)) > + error = -EFAULT; and I guess you can simplify this code a bit, anon_name = madvise_get_anon_name(...); if (!anon_name || copy_to_user(...)) error = -EFAULT; mmap_read_unlock(mm); anon_vma_name_put(anon_name); // safe if anon_name == NULL; > +const struct anon_vma_name *madvise_get_anon_name(struct mm_struct *mm, > + unsigned long start) > +{ > + struct vm_area_struct *vma; > + struct anon_vma_name *anon_name; > + > + vma = find_vma(mm, start); > + if (vma) { > + anon_name = anon_vma_name(vma); > + if (anon_name) { > + anon_vma_name_get(anon_name); > + return anon_name; > + } > + } > + > + return NULL; Again, afaics this can be simplified, struct anon_vma_name *anon_name = NULL; vma = find_vma(mm, start); if (vma) { anon_name = anon_vma_name(vma); anon_vma_name_get(anon_name); } return anon_name; Oleg.