The patch titled
Subject: mm/page_owner: use scnprintf() to avoid excessive buffer overrun check
has been added to the -mm tree. Its filename is
mm-page_owner-use-scnprintf-to-avoid-excessive-buffer-overrun-check.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-page_owner-use-scnprintf-to-avoid-excessive-buffer-overrun-check.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-page_owner-use-scnprintf-to-avoid-excessive-buffer-overrun-check.patch
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------------------------------------------------------
From: Waiman Long <longman@xxxxxxxxxx>
Subject: mm/page_owner: use scnprintf() to avoid excessive buffer overrun check
The snprintf() function can return a length greater than the given input
size. That will require a check for buffer overrun after each invocation
of snprintf(). scnprintf(), on the other hand, will never return a
greater length. By using scnprintf() in selected places, we can avoid
some buffer overrun checks except after stack_depot_snprint() and after
the last snprintf().
Link: https://lkml.kernel.org/r/20220202203036.744010-3-longman@xxxxxxxxxx
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Reviewed-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Rafael Aquini <aquini@xxxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_owner.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)
--- a/mm/page_owner.c~mm-page_owner-use-scnprintf-to-avoid-excessive-buffer-overrun-check
+++ a/mm/page_owner.c
@@ -338,19 +338,16 @@ print_page_owner(char __user *buf, size_
if (!kbuf)
return -ENOMEM;
- ret = snprintf(kbuf, count,
+ ret = scnprintf(kbuf, count,
"Page allocated via order %u, mask %#x(%pGg), pid %d, ts %llu ns, free_ts %llu ns\n",
page_owner->order, page_owner->gfp_mask,
&page_owner->gfp_mask, page_owner->pid,
page_owner->ts_nsec, page_owner->free_ts_nsec);
- if (ret >= count)
- goto err;
-
/* Print information relevant to grouping pages by mobility */
pageblock_mt = get_pageblock_migratetype(page);
page_mt = gfp_migratetype(page_owner->gfp_mask);
- ret += snprintf(kbuf + ret, count - ret,
+ ret += scnprintf(kbuf + ret, count - ret,
"PFN %lu type %s Block %lu type %s Flags %pGp\n",
pfn,
migratetype_names[page_mt],
@@ -358,19 +355,14 @@ print_page_owner(char __user *buf, size_
migratetype_names[pageblock_mt],
&page->flags);
- if (ret >= count)
- goto err;
-
ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
if (ret >= count)
goto err;
if (page_owner->last_migrate_reason != -1) {
- ret += snprintf(kbuf + ret, count - ret,
+ ret += scnprintf(kbuf + ret, count - ret,
"Page has been migrated, last migrate reason: %s\n",
migrate_reason_names[page_owner->last_migrate_reason]);
- if (ret >= count)
- goto err;
}
ret += snprintf(kbuf + ret, count - ret, "\n");
_
Patches currently in -mm which might be from longman@xxxxxxxxxx are
lib-vsprintf-avoid-redundant-work-with-0-size.patch
mm-page_owner-use-scnprintf-to-avoid-excessive-buffer-overrun-check.patch
mm-page_owner-print-memcg-information.patch
mm-page_owner-record-task-command-name.patch
mm-sparsemem-fix-mem_section-will-never-be-null-gcc-12-warning.patch
ipc-mqueue-use-get_tree_nodev-in-mqueue_get_tree.patch
