OpenE2K/linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

proc-vmcore: wrong data type casting fix

Browse Source 
On i686 PAE enabled machine the contiguous physical area could be large
and it can cause trimming down variables in below calculation in
read_vmcore() and mmap_vmcore():

	tsz = min_t(size_t, m->offset + m->size - *fpos, buflen);

That is, the types being used is like below on i686:
m->offset: unsigned long long int
m->size:   unsigned long long int
*fpos:     loff_t (long long int)
buflen:    size_t (unsigned int)

So casting (m->offset + m->size - *fpos) by size_t means truncating a
given value by 4GB.

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.
Similarly we could also get other truncated values less than buflen.
Then the real size passed down is not correct any more.

If (m->offset + m->size - *fpos) is above 4GB, read_vmcore or
mmap_vmcore use the min_t result with truncated values being compared to
buflen.  Then, fpos proceeds with the wrong value so that we reach below
bugs:

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 in are not
truncated.

Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Dave Young <dyoung@redhat.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jianyu Zhan <nasa4836@gmail.com>
Cc: Minfei Huang <mhuang@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dave Young 2016-03-17 14:21:03 -07:00 committed by Linus Torvalds
parent 7e2bc81da3
commit 0b50a2d86d
1 changed files with 5 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
fs/proc/vmcore.c
View File

@ -231,7 +231,9 @@ static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos,
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, struct vm_area_struct *vma)
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,