diff options
| author | Dave Young <dyoung@redhat.com> | 2016-03-17 21:21:03 (GMT) |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-03-17 22:09:34 (GMT) |
| commit | 0b50a2d86d8e9a6d58e2ca3e5657f962eb698d2f (patch) | |
| tree | 3df4d5824d8abc91faf32f27a1f1293d041ac784 /fs/proc | |
| parent | 7e2bc81da333f0d4ca68882fdaef41e1b0d5690d (diff) | |
| download | linux-0b50a2d86d8e9a6d58e2ca3e5657f962eb698d2f.tar.xz | |
proc-vmcore: wrong data type casting fix
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>
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/vmcore.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 4e61388..55bb57e 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -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, |