[PATCH] ubifs: fix snprintf() checking

From: Dan Carpenter
Date: Tue May 11 2021 - 03:12:51 EST


The snprintf() function returns the number of characters (not
counting the NUL terminator) that it would have printed if we
had space.

This buffer has UBIFS_DFS_DIR_LEN characters plus one extra for
the terminator. Printing UBIFS_DFS_DIR_LEN is okay but anything
higher will result in truncation. Thus the comparison needs to be
change from == to >.

These strings are compile time constants so this patch doesn't
affect runtime.

Fixes: ae380ce04731 ("UBIFS: lessen the size of debugging info data structure")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
drivers/mtd/ubi/debug.c | 2 +-
fs/ubifs/debug.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c
index ac2bdba8bb1a..3c0c8eca4d51 100644
--- a/drivers/mtd/ubi/debug.c
+++ b/drivers/mtd/ubi/debug.c
@@ -511,7 +511,7 @@ int ubi_debugfs_init_dev(struct ubi_device *ubi)

n = snprintf(d->dfs_dir_name, UBI_DFS_DIR_LEN + 1, UBI_DFS_DIR_NAME,
ubi->ubi_num);
- if (n == UBI_DFS_DIR_LEN) {
+ if (n > UBI_DFS_DIR_LEN) {
/* The array size is too small */
return -EINVAL;
}
diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 1bbb9fe661b1..fc718f6178f2 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -2824,7 +2824,7 @@ void dbg_debugfs_init_fs(struct ubifs_info *c)

n = snprintf(d->dfs_dir_name, UBIFS_DFS_DIR_LEN + 1, UBIFS_DFS_DIR_NAME,
c->vi.ubi_num, c->vi.vol_id);
- if (n == UBIFS_DFS_DIR_LEN) {
+ if (n > UBIFS_DFS_DIR_LEN) {
/* The array size is too small */
return;
}
--
2.30.2