On Tue, Jul 14, 2015 at 06:37:47PM +0300, Konstantin Khlebnikov wrote:
quoted hunk ↗ jump to hunk
This patch makes pagemap readable for normal users and hides physical
addresses from them. For some use-cases PFN isn't required at all.
Signed-off-by: Konstantin Khlebnikov <redacted>
Fixes: ab676b7d6fbf ("pagemap: do not leak physical addresses to non-privileged userspace")
Link: http://lkml.kernel.org/r/1425935472-17949-1-git-send-email-kirill@shutemov.name
---
fs/proc/task_mmu.c | 25 ++++++++++++++-----------
1 file changed, 14 insertions(+), 11 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 040721fa405a..3a5d338ea219 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -937,6 +937,7 @@ typedef struct {
struct pagemapread {
int pos, len; /* units: PM_ENTRY_BYTES, not bytes */
pagemap_entry_t *buffer;
+ bool show_pfn;
};
#define PAGEMAP_WALK_SIZE (PMD_SIZE)@@ -1013,7 +1014,8 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm,
struct page *page = NULL;
if (pte_present(pte)) {
- frame = pte_pfn(pte);
+ if (pm->show_pfn)
+ frame = pte_pfn(pte);
flags |= PM_PRESENT;
page = vm_normal_page(vma, addr, pte);
if (pte_soft_dirty(pte))
Don't you need the same if (pm->show_pfn) check in is_swap_pte path, too?
(although I don't think that it can be exploited by row hammer attack ...)
Thanks,
Naoya Horiguchi
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