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authorWaiman Long <longman@redhat.com>2022-03-25 02:09:05 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-25 03:06:44 +0100
commit3ebc439761273274ea00258da84d997841f01e72 (patch)
tree51a18a4926910acceb7b14446f1a35ccc94ef482 /mm/page_owner.c
parentlib/vsprintf: avoid redundant work with 0 size (diff)
downloadlinux-3ebc439761273274ea00258da84d997841f01e72.tar.xz
linux-3ebc439761273274ea00258da84d997841f01e72.zip
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@redhat.com Signed-off-by: Waiman Long <longman@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> Acked-by: Rafael Aquini <aquini@redhat.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Steven Rostedt (Google) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
-rw-r--r--mm/page_owner.c14
1 files changed, 3 insertions, 11 deletions
diff --git a/mm/page_owner.c b/mm/page_owner.c
index 99e360df9465..28dac73e0542 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -338,19 +338,16 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
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_t count, unsigned long pfn,
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");