[PATCH v2 3/3] lib/bootconfig: fix snprintf truncation check in xbc_node_compose_key_after()

[Josh Law <hlcj1234567@gmail.com>]

From: Josh Law <objecting@objecting.org>

snprintf() returns the number of characters that would have been
written excluding the NUL terminator.  Output is truncated when the
return value is >= the buffer size, not just > the buffer size.

When ret == size, the current code takes the non-truncated path,
advancing buf by ret and reducing size to 0.  This is wrong because
the output was actually truncated (the last character was replaced by
NUL).  Fix by using >= so the truncation path is taken correctly.

Signed-off-by: Josh Law <objecting@objecting.org>
---
 lib/bootconfig.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/bootconfig.c b/lib/bootconfig.c
index 62b4ed7a0ba6..b0ef1e74e98a 100644
--- a/lib/bootconfig.c
+++ b/lib/bootconfig.c
@@ -316,7 +316,7 @@ int __init xbc_node_compose_key_after(struct xbc_node *root,
 			       depth ? "." : "");
 		if (ret < 0)
 			return ret;
-		if (ret > size) {
+		if (ret >= size) {
 			size = 0;
 		} else {
 			size -= ret;
-- 
2.34.1