From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1aeIUM-00047h-L2 for kexec@lists.infradead.org; Fri, 11 Mar 2016 08:32:03 +0000 Date: Fri, 11 Mar 2016 16:31:33 +0800 From: Baoquan He Subject: Re: [PATCH] proc-vmcore: wrong data type casting fix Message-ID: <20160311083133.GA3207@x1.redhat.com> References: <20160311081501.GA9147@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20160311081501.GA9147@dhcp-128-65.nay.redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Dave Young Cc: kexec@lists.infradead.org, nasa4836@gmail.com, linux-kernel@vger.kernel.org, d.hatayama@jp.fujitsu.com, Andrew Morton , vgoyal@redhat.com On 03/11/16 at 04:15pm, Dave Young wrote: > On i686 PAE enabled machine the contiguous physical area could be large > and it can cause triming down variables in below calculation in > read_vmcore() and mmap_vmcore(): > > tsz = min_t(size_t, m->offset + m->size - *fpos, buflen); > > Then the real size passed down is not correct any more. > Suppose m->offset + m->size - *fpos being truncated to 0, buflen >0 then > we will get tsz = 0. It is of course not an expected result. > > During out test there are two problems caused by it: ~ our > 1) read_vmcore will refuse to continue so makedumpfile fails. > 2) mmap_vmcore will trigger BUG_ON() in remap_pfn_range(). > > Use unsigned long long in min_t instead so that the variables are not > truncated. > > Signed-off-by: Baoquan He > Signed-off-by: Dave Young > --- > fs/proc/vmcore.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > --- linux-x86.orig/fs/proc/vmcore.c > +++ linux-x86/fs/proc/vmcore.c > @@ -231,7 +231,9 @@ static ssize_t __read_vmcore(char *buffe > > list_for_each_entry(m, &vmcore_list, list) { > if (*fpos < m->offset + m->size) { > - tsz = min_t(size_t, m->offset + m->size - *fpos, buflen); > + tsz = (size_t)min_t(unsigned long long, > + m->offset + m->size - *fpos, > + buflen); > start = m->paddr + *fpos - m->offset; > tmp = read_from_oldmem(buffer, tsz, &start, userbuf); > if (tmp < 0) > @@ -461,7 +463,8 @@ static int mmap_vmcore(struct file *file > if (start < m->offset + m->size) { > u64 paddr = 0; > > - tsz = min_t(size_t, m->offset + m->size - start, size); > + tsz = (size_t)min_t(unsigned long long, > + m->offset + m->size - start, size); > paddr = m->paddr + start - m->offset; > if (vmcore_remap_oldmem_pfn(vma, vma->vm_start + len, > paddr >> PAGE_SHIFT, tsz, _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec