File libhugetlbfs_PR77.patch of Package libhugetlbfs

From f4c8a83e674738a8b30fcb6336d4389236dedc90 Mon Sep 17 00:00:00 2001
From: Thomas Abraham <tabraham@suse.com>
Date: Wed, 9 Aug 2023 13:26:39 -0400
Subject: [PATCH] hugeutils: allow for long mount entries in find_mounts

The buffer used for parsing the mount list is not large enough.

In container environments using overlay filesystems, the use of a
large number of layers can easily result in valid entries which
exceed the buffer size resulting in 'Line too long when parsing mounts'
errors and the mount list not being processed completely.
---
 hugeutils.c | 59 +++++++++++++----------------------------------------
 1 file changed, 14 insertions(+), 45 deletions(-)

diff --git a/hugeutils.c b/hugeutils.c
index 0230976..c8ba455 100644
--- a/hugeutils.c
+++ b/hugeutils.c
@@ -44,6 +44,7 @@
 #include <linux/types.h>
 #include <linux/unistd.h>
 #include <dirent.h>
+#include <mntent.h>
 
 #include "libhugetlbfs_internal.h"
 #include "hugetlbfs.h"
@@ -617,62 +618,30 @@ void debug_show_page_sizes(void)
 			hpage_sizes[i].mount);
 }
 
-#define LINE_MAXLEN	2048
 static void find_mounts(void)
 {
-	int fd;
-	char path[PATH_MAX+1];
-	char line[LINE_MAXLEN + 1];
-	char *eol;
-	char *match;
-	char *end;
-	int bytes;
-	off_t offset;
-
-	fd = open("/proc/mounts", O_RDONLY);
-	if (fd < 0) {
-		fd = open("/etc/mtab", O_RDONLY);
-		if (fd < 0) {
+	FILE *f;
+	struct mntent *mnt;
+	char *fstype = "hugetlbfs";
+
+	f = fopen("/proc/mounts", "r");
+	if (!f) {
+		f = fopen("/etc/mtab", "r");
+		if (!f) {
 			ERROR("Couldn't open /proc/mounts or /etc/mtab (%s)\n",
 				strerror(errno));
 			return;
 		}
 	}
 
-	while ((bytes = read(fd, line, LINE_MAXLEN)) > 0) {
-		line[LINE_MAXLEN] = '\0';
-		eol = strchr(line, '\n');
-		if (!eol) {
-			ERROR("Line too long when parsing mounts\n");
-			break;
-		}
-
-		/*
-		 * Truncate the string to just one line and reset the file
-		 * to begin reading at the start of the next line.
-		 */
-		*eol = '\0';
-		offset = bytes - (eol + 1 - line);
-		lseek(fd, -offset, SEEK_CUR);
-
-		/* Match only hugetlbfs filesystems. */
-		match = strstr(line, " hugetlbfs ");
-		if (match) {
-			match = strchr(line, '/');
-			if (!match)
-				continue;
-			end = strchr(match, ' ');
-			if (!end)
-				continue;
-
-			strncpy(path, match, end - match);
-			path[end - match] = '\0';
-			if ((hugetlbfs_test_path(path) == 1) &&
+	while ((mnt = getmntent(f))) {
+		if (!strncmp(mnt->mnt_type, fstype, sizeof(fstype))) {
+			if ((hugetlbfs_test_path(mnt->mnt_dir) == 1) &&
 			    !(access(path, R_OK | W_OK | X_OK)))
-				add_hugetlbfs_mount(path, 0);
+				add_hugetlbfs_mount(mnt->mnt_dir, 0);
 		}
 	}
-	close(fd);
+	fclose(f);
 }
 
 void setup_mounts(void)