From 54910d33ba7d1420e39662d0643eea156eac1187 Mon Sep 17 00:00:00 2001 From: HushBugger Date: Tue, 16 Aug 2022 22:37:50 +0200 Subject: [PATCH] Fix buffer over-read in decode() The format specifier for parsing percent-formatted characters uses a maximum number of digits, not an exact number of digits. If the hex number has only one digit this will skip a character, potentially pointing past the terminating null byte. --- http.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/http.c b/http.c index 5b9dade..bd58c4f 100644 --- a/http.c +++ b/http.c @@ -136,7 +136,9 @@ decode(const char src[PATH_MAX], char dest[PATH_MAX]) const char *s; for (s = src, i = 0; *s; s++, i++) { - if (*s == '%' && (sscanf(s + 1, "%2hhx", &n) == 1)) { + if (*s == '%' && isxdigit((unsigned char)s[1]) && + isxdigit((unsigned char)s[2])) { + sscanf(s + 1, "%2hhx", &n); dest[i] = n; s += 2; } else { -- 2.30.2