Fix off-by-one in postdecode_fields

Fixes following error found by fuzzer:

 ERROR: AddressSanitizer: SEGV on unknown address 0x60c000120000 (pc 0x00000054f64f bp 0x000000000008 sp 0x7ffe4fc2c120 T0)
 The signal is caused by a READ memory access.
    #0 0x54f64f in postdecode_fields cgi-io/util.c:93:7
    #1 0x54f382 in LLVMFuzzerTestOneInput cgi-io/tests/fuzz/test-fuzz.c:36:6

That is caused by reading 1 byte past the size of the buffer.

Signed-off-by: Petr Štetiar <ynezz@true.cz>

diff --git a/tests/fuzz/corpus/crash-9adc1b00fe9189d66d3bfd8b7759b003cf3f5427 b/tests/fuzz/corpus/crash-9adc1b00fe9189d66d3bfd8b7759b003cf3f5427
new file mode 100644 (file)
index 0000000..7122f99
Binary files /dev/null and b/tests/fuzz/corpus/crash-9adc1b00fe9189d66d3bfd8b7759b003cf3f5427 differ

diff --git a/tests/fuzz/corpus/crash-c1e3b9cd71f83cc0de5ab4c0e3db39316cd5c6c0 b/tests/fuzz/corpus/crash-c1e3b9cd71f83cc0de5ab4c0e3db39316cd5c6c0
new file mode 100644 (file)
index 0000000..264f4b1
--- /dev/null
+++ b/tests/fuzz/corpus/crash-c1e3b9cd71f83cc0de5ab4c0e3db39316cd5c6c0
@@ -0,0 +1 @@
+±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±

diff --git a/util.c b/util.c
index e8627589b49af5613f2fd3bf236cc17571012d7a..419ed16a52d5a68519cfafda48a9cdd1420dcee5 100644 (file)
--- a/util.c
+++ b/util.c
@@ -88,7 +88,7 @@ postdecode_fields(char *postbuf, ssize_t len, char **fields, int n_fields)
        char *p;
        int i, field, found = 0;
 
-       for (p = postbuf, i = 0; i <= len; i++)
+       for (p = postbuf, i = 0; i < len; i++)
        {
                if (postbuf[i] == '=')
                {