[PATCH] lib/vsprintf: Require exact hash_pointers mode matches

[Kaitao Cheng <kaitao.cheng@linux.dev>]

From: Kaitao Cheng <chengkaitao@kylinos.cn>

hash_pointers= accepts a small set of mode strings, but the parser uses
strncmp() with the length of each valid mode.  That accepts values with
trailing garbage, such as hash_pointers=autobots or
hash_pointers=nevermind, as valid aliases for auto and never.

Use strcmp() so that only the documented mode strings are accepted.
Invalid values will continue to fall back to auto through the existing
unknown-mode path.

Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
---
 lib/vsprintf.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 9ca676feb8eb..03e87b933fd0 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -2354,13 +2354,13 @@ static int __init hash_pointers_mode_parse(char *str)
 	if (!str) {
 		pr_warn("Hash pointers mode empty; falling back to auto.\n");
 		hash_pointers_mode = HASH_PTR_AUTO;
-	} else if (strncmp(str, "auto", 4) == 0)   {
+	} else if (strcmp(str, "auto") == 0) {
 		pr_info("Hash pointers mode set to auto.\n");
 		hash_pointers_mode = HASH_PTR_AUTO;
-	} else if (strncmp(str, "never", 5) == 0) {
+	} else if (strcmp(str, "never") == 0) {
 		pr_info("Hash pointers mode set to never.\n");
 		hash_pointers_mode = HASH_PTR_NEVER;
-	} else if (strncmp(str, "always", 6) == 0) {
+	} else if (strcmp(str, "always") == 0) {
 		pr_info("Hash pointers mode set to always.\n");
 		hash_pointers_mode = HASH_PTR_ALWAYS;
 	} else {
-- 
2.50.1 (Apple Git-155)