The patch titled
Subject: mm: pagemap_read: limit scan to virtual region being asked
has been added to the -mm tree. Its filename is
mm-pagemap-limit-scan-to-virtual-region-being-asked.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-pagemap-limit-scan-to-virtual-region-being-asked.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-pagemap-limit-scan-to-virtual-region-being-asked.patch
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------------------------------------------------------
From: Shiraz Hashim <shashim@xxxxxxxxxxxxxx>
Subject: mm: pagemap_read: limit scan to virtual region being asked
pagemap_read scans through the virtual address space of a task until it
prepares 'count' pagemaps or it reaches end of task.
This presents a problem when the page walk doesn't happen for a vma with
VM_PFNMAP set. In this case the walk is silently skipped and no pagemap
is prepared, in turn making pagemap_read scan through to 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 <shashim@xxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff -puN fs/proc/task_mmu.c~mm-pagemap-limit-scan-to-virtual-region-being-asked fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~mm-pagemap-limit-scan-to-virtual-region-being-asked
+++ a/fs/proc/task_mmu.c
@@ -1254,7 +1254,9 @@ static ssize_t pagemap_read(struct file
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)
_
Patches currently in -mm which might be from shashim@xxxxxxxxxxxxxx are
mm-pagemap-limit-scan-to-virtual-region-being-asked.patch
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