linux-kernel - [PATCH V3 6/8] mm: and drivers core: Convert hugetlb_report_node_meminfo to sysfs

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Date:   Wed, 16 Sep 2020 13:40:43 -0700
From:   Joe Perches <joe@...ches.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Denis Efremov <efremov@...ux.com>,
        Julia Lawall <julia.lawall@...ia.fr>,
        Alex Dewar <alex.dewar90@...il.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH V3 6/8] mm: and drivers core: Convert hugetlb_report_node_meminfo to sysfs_emit

Convert the unbound sprintf in hugetlb_report_node_meminfo to use
sysfs_emit_at so that no possible overrun of a PAGE_SIZE buf can occur.

Signed-off-by: Joe Perches <joe@...ches.com>
---
 drivers/base/node.c     |  2 +-
 include/linux/hugetlb.h |  4 ++--
 mm/hugetlb.c            | 18 ++++++++++--------
 3 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index b33526a9fcfc..dafe03e82e7c 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -473,7 +473,7 @@ static ssize_t node_read_meminfo(struct device *dev,
 				    HPAGE_PMD_NR)
 #endif
 			    );
-	len += hugetlb_report_node_meminfo(nid, buf + len);
+	len += hugetlb_report_node_meminfo(buf, len, nid);
 	return len;
 }
 
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index d5cc5f802dd4..ebca2ef02212 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -129,7 +129,7 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 				unsigned long start, unsigned long end,
 				struct page *ref_page);
 void hugetlb_report_meminfo(struct seq_file *);
-int hugetlb_report_node_meminfo(int, char *);
+int hugetlb_report_node_meminfo(char *buf, int len, int nid);
 void hugetlb_show_meminfo(void);
 unsigned long hugetlb_total_pages(void);
 vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
@@ -245,7 +245,7 @@ static inline void hugetlb_report_meminfo(struct seq_file *m)
 {
 }
 
-static inline int hugetlb_report_node_meminfo(int nid, char *buf)
+static inline int hugetlb_report_node_meminfo(char *buf, int len, int nid)
 {
 	return 0;
 }
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 61469fd3ad92..fe76f8fd5a73 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3571,18 +3571,20 @@ void hugetlb_report_meminfo(struct seq_file *m)
 	seq_printf(m, "Hugetlb:        %8lu kB\n", total / 1024);
 }
 
-int hugetlb_report_node_meminfo(int nid, char *buf)
+int hugetlb_report_node_meminfo(char *buf, int len, int nid)
 {
 	struct hstate *h = &default_hstate;
+
 	if (!hugepages_supported())
 		return 0;
-	return sprintf(buf,
-		"Node %d HugePages_Total: %5u\n"
-		"Node %d HugePages_Free:  %5u\n"
-		"Node %d HugePages_Surp:  %5u\n",
-		nid, h->nr_huge_pages_node[nid],
-		nid, h->free_huge_pages_node[nid],
-		nid, h->surplus_huge_pages_node[nid]);
+
+	return sysfs_emit_at(buf, len,
+			     "Node %d HugePages_Total: %5u\n"
+			     "Node %d HugePages_Free:  %5u\n"
+			     "Node %d HugePages_Surp:  %5u\n",
+			     nid, h->nr_huge_pages_node[nid],
+			     nid, h->free_huge_pages_node[nid],
+			     nid, h->surplus_huge_pages_node[nid]);
 }
 
 void hugetlb_show_meminfo(void)
-- 
2.26.0