[PATCH] xfs: Use scnprintf() for avoiding potential buffer overflow

Takashi Iwai
2020-03-11T09:35:55Z

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit. Fix it by replacing with scnprintf().

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
fs/xfs/xfs_stats.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/xfs_stats.c b/fs/xfs/xfs_stats.c
index 113883c4f202..f70f1255220b 100644
--- a/fs/xfs/xfs_stats.c
+++ b/fs/xfs/xfs_stats.c
@@ -57,13 +57,13 @@ int xfs_stats_format(struct xfsstats __percpu *stats, char *buf)
/* Loop over all stats groups */

for (i = j = 0; i < ARRAY_SIZE(xstats); i++) {
- len += snprintf(buf + len, PATH_MAX - len, "%s",
+ len += scnprintf(buf + len, PATH_MAX - len, "%s",
xstats[i].desc);
/* inner loop does each group */
for (; j < xstats[i].endpoint; j++)
- len += snprintf(buf + len, PATH_MAX - len, " %u",
+ len += scnprintf(buf + len, PATH_MAX - len, " %u",
counter_val(stats, j));
- len += snprintf(buf + len, PATH_MAX - len, "\n");
+ len += scnprintf(buf + len, PATH_MAX - len, "\n");
}
/* extra precision counters */
for_each_possible_cpu(i) {
@@ -72,9 +72,9 @@ int xfs_stats_format(struct xfsstats __percpu *stats, char *buf)
xs_read_bytes += per_cpu_ptr(stats, i)->s.xs_read_bytes;
}

- len += snprintf(buf + len, PATH_MAX-len, "xpc %Lu %Lu %Lu\n",
+ len += scnprintf(buf + len, PATH_MAX-len, "xpc %Lu %Lu %Lu\n",
xs_xstrat_bytes, xs_write_bytes, xs_read_bytes);
- len += snprintf(buf + len, PATH_MAX-len, "debug %u\n",
+ len += scnprintf(buf + len, PATH_MAX-len, "debug %u\n",
#if defined(DEBUG)
1);
#else
--
2.16.4