kcore: /proc/kcore should use vread

/proc/kcore has its own routine to access vmallc area.  It can be replaced
with vread().  And by this, /proc/kcore can do safe access to vmalloc
area.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Mike Smith <scgtrp@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 33 deletions

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 59b43a068872..f06f45b42181 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -328,43 +328,12 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
                                 return -EFAULT;
                 } else if (is_vmalloc_addr((void *)start)) {
                         char * elf_buf;
-                        struct vm_struct *m;
-                        unsigned long curstart = start;
-                        unsigned long cursize = tsz;
 
                         elf_buf = kzalloc(tsz, GFP_KERNEL);
                         if (!elf_buf)
                                 return -ENOMEM;
-
-                        read_lock(&vmlist_lock);
-                        for (m=vmlist; m && cursize; m=m->next) {
-                                unsigned long vmstart;
-                                unsigned long vmsize;
-                                unsigned long msize = m->size - PAGE_SIZE;
-
-                                if (((unsigned long)m->addr + msize) < 
-                                                                curstart)
-                                        continue;
-                                if ((unsigned long)m->addr > (curstart + 
-                                                                cursize))
-                                        break;
-                                vmstart = (curstart < (unsigned long)m->addr ? 
-                                        (unsigned long)m->addr : curstart);
-                                if (((unsigned long)m->addr + msize) > 
-                                                        (curstart + cursize))
-                                        vmsize = curstart + cursize - vmstart;
-                                else
-                                        vmsize = (unsigned long)m->addr + 
-                                                        msize - vmstart;
-                                curstart = vmstart + vmsize;
-                                cursize -= vmsize;
-                                /* don't dump ioremap'd stuff! (TA) */
-                                if (m->flags & VM_IOREMAP)
-                                        continue;
-                                memcpy(elf_buf + (vmstart - start),
-                                        (char *)vmstart, vmsize);
-                        }
-                        read_unlock(&vmlist_lock);
+                        vread(elf_buf, (char *)start, tsz);
+                        /* we have to zero-fill user buffer even if no read */
                         if (copy_to_user(buffer, elf_buf, tsz)) {
                                 kfree(elf_buf);
                                 return -EFAULT;