From 0b50a2d86d8e9a6d58e2ca3e5657f962eb698d2f Mon Sep 17 00:00:00 2001 From: Dave Young Date: Thu, 17 Mar 2016 14:21:03 -0700 Subject: [PATCH] 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 Signed-off-by: Dave Young Cc: HATAYAMA Daisuke Cc: Vivek Goyal Cc: Jianyu Zhan Cc: Minfei Huang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/vmcore.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 4e61388ec03d..55bb57e6a30d 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, -- 2.20.1