The patch titled
Subject: mm/rmap: fix signedness bug in make_device_exclusive_range()
has been added to the -mm tree. Its filename is
mm-device-exclusive-memory-access-fix.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-device-exclusive-memory-access-fix.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-device-exclusive-memory-access-fix.patch
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------------------------------------------------------
From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Subject: mm/rmap: fix signedness bug in make_device_exclusive_range()
The get_user_pages_remote() function returns a long type, but we are using
"unsigned long i;" as the list iterator. If "npages" is -ENOMEM, the
comparison "i < npages" is type promoted and "npages" becomes a very high
positive value. The loop will then iterate until the kernel crashes.
There are two ways to fix this. Declare "i" as a long type or add an
explicit check for get_user_pages_remote() error returns. Either approach
will work so let's do both.
Link: https://lkml.kernel.org/r/YNIz5NVnZ5GiZ3u1@mwanda
Fixes: fa1e686e5f53 ("mm: device exclusive memory access")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/rmap.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/mm/rmap.c~mm-device-exclusive-memory-access-fix
+++ a/mm/rmap.c
@@ -2187,11 +2187,14 @@ int make_device_exclusive_range(struct m
void *owner)
{
long npages = (end - start) >> PAGE_SHIFT;
- unsigned long i;
+ long i;
npages = get_user_pages_remote(mm, start, npages,
FOLL_GET | FOLL_WRITE | FOLL_SPLIT_PMD,
pages, NULL, NULL);
+ if (npages < 0)
+ return npages;
+
for (i = 0; i < npages; i++, start += PAGE_SIZE) {
if (!trylock_page(pages[i])) {
put_page(pages[i]);
_
Patches currently in -mm which might be from dan.carpenter@xxxxxxxxxx are
ocfs2-fix-snprintf-checking.patch
mm-thp-refactor-numa-fault-handling-fix.patch
mm-device-exclusive-memory-access-fix.patch
