pagemap_read scans through the virtual address space of a
task till it prepares 'count' pagemaps or it reaches end
of task.
This presents a problem when the page walk doesn't happen
for vma with VM_PFNMAP set. In which case walk is silently
skipped and no pagemap is prepare, in turn making
pagemap_read to scan through task end, even crossing beyond
'count', landing into a different vma region. This leads to
wrong presentation of mappings for that vma.
Fix this by limiting end_vaddr to the end of the virtual
address region being scanned.
Signed-off-by: Shiraz Hashim <shas...@codeaurora.org>
---
fs/proc/task_mmu.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 246eae8..04362e4 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1270,7 +1270,9 @@ static ssize_t pagemap_read(struct file *file, char
__user *buf,
src = *ppos;
svpfn = src / PM_ENTRY_BYTES;
start_vaddr = svpfn << PAGE_SHIFT;
- end_vaddr = TASK_SIZE_OF(task);
+ end_vaddr = start_vaddr + ((count / PM_ENTRY_BYTES) << PAGE_SHIFT);
+ if ((end_vaddr > TASK_SIZE_OF(task)) || (end_vaddr < start_vaddr))
+ end_vaddr = TASK_SIZE_OF(task);
/* watch out for wraparound */
if (svpfn > TASK_SIZE_OF(task) >> PAGE_SHIFT)
--
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