From: Oleg Nesterov <oleg@redhat.com> To: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Cc: mpe@ellerman.id.au, rostedt@goodmis.org, paulus@samba.org, jniethe5@gmail.com, naveen.n.rao@linux.ibm.com, sandipan@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] powerpc/uprobes: Don't allow probe on suffix of prefixed instruction Date: Tue, 19 Jan 2021 18:26:03 +0100 [thread overview] Message-ID: <20210119172603.GA16696@redhat.com> (raw) In-Reply-To: <20210119091234.76317-1-ravi.bangoria@linux.ibm.com> On 01/19, Ravi Bangoria wrote: > > Probe on 2nd word of a prefixed instruction is invalid scenario and > should be restricted. I don't understand this ppc-specific problem, but... > +#ifdef CONFIG_PPC64 > +int arch_uprobe_verify_opcode(struct page *page, unsigned long vaddr, > + uprobe_opcode_t opcode) > +{ > + uprobe_opcode_t prefix; > + void *kaddr; > + struct ppc_inst inst; > + > + /* Don't check if vaddr is pointing to the beginning of page */ > + if (!(vaddr & ~PAGE_MASK)) > + return 0; So the fix is incomplete? Or insn at the start of page can't be prefixed? > +int __weak arch_uprobe_verify_opcode(struct page *page, unsigned long vaddr, > + uprobe_opcode_t opcode) > +{ > + return 0; > +} > + > static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) > { > uprobe_opcode_t old_opcode; > @@ -275,6 +281,8 @@ static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t > if (is_swbp_insn(new_opcode)) { > if (is_swbp) /* register: already installed? */ > return 0; > + if (arch_uprobe_verify_opcode(page, vaddr, old_opcode)) > + return -EINVAL; Well, this doesn't look good... To me it would be better to change the prepare_uprobe() path to copy the potential prefix into uprobe->arch and check ppc_inst_prefixed() in arch_uprobe_analyze_insn(). What do you think? Oleg.
WARNING: multiple messages have this Message-ID (diff)
From: Oleg Nesterov <oleg@redhat.com> To: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Cc: linux-kernel@vger.kernel.org, rostedt@goodmis.org, paulus@samba.org, sandipan@linux.ibm.com, jniethe5@gmail.com, naveen.n.rao@linux.ibm.com, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] powerpc/uprobes: Don't allow probe on suffix of prefixed instruction Date: Tue, 19 Jan 2021 18:26:03 +0100 [thread overview] Message-ID: <20210119172603.GA16696@redhat.com> (raw) In-Reply-To: <20210119091234.76317-1-ravi.bangoria@linux.ibm.com> On 01/19, Ravi Bangoria wrote: > > Probe on 2nd word of a prefixed instruction is invalid scenario and > should be restricted. I don't understand this ppc-specific problem, but... > +#ifdef CONFIG_PPC64 > +int arch_uprobe_verify_opcode(struct page *page, unsigned long vaddr, > + uprobe_opcode_t opcode) > +{ > + uprobe_opcode_t prefix; > + void *kaddr; > + struct ppc_inst inst; > + > + /* Don't check if vaddr is pointing to the beginning of page */ > + if (!(vaddr & ~PAGE_MASK)) > + return 0; So the fix is incomplete? Or insn at the start of page can't be prefixed? > +int __weak arch_uprobe_verify_opcode(struct page *page, unsigned long vaddr, > + uprobe_opcode_t opcode) > +{ > + return 0; > +} > + > static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) > { > uprobe_opcode_t old_opcode; > @@ -275,6 +281,8 @@ static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t > if (is_swbp_insn(new_opcode)) { > if (is_swbp) /* register: already installed? */ > return 0; > + if (arch_uprobe_verify_opcode(page, vaddr, old_opcode)) > + return -EINVAL; Well, this doesn't look good... To me it would be better to change the prepare_uprobe() path to copy the potential prefix into uprobe->arch and check ppc_inst_prefixed() in arch_uprobe_analyze_insn(). What do you think? Oleg.
next prev parent reply other threads:[~2021-01-19 18:29 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-01-19 9:12 [PATCH] powerpc/uprobes: Don't allow probe on suffix of prefixed instruction Ravi Bangoria 2021-01-19 9:12 ` Ravi Bangoria 2021-01-19 17:26 ` Oleg Nesterov [this message] 2021-01-19 17:26 ` Oleg Nesterov 2021-01-20 11:18 ` Ravi Bangoria 2021-01-20 11:18 ` Ravi Bangoria
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20210119172603.GA16696@redhat.com \ --to=oleg@redhat.com \ --cc=jniethe5@gmail.com \ --cc=linux-kernel@vger.kernel.org \ --cc=linuxppc-dev@lists.ozlabs.org \ --cc=mpe@ellerman.id.au \ --cc=naveen.n.rao@linux.ibm.com \ --cc=paulus@samba.org \ --cc=ravi.bangoria@linux.ibm.com \ --cc=rostedt@goodmis.org \ --cc=sandipan@linux.ibm.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.