[PATCH] util/cutils: Silent Coverity array overrun warning in freq_to_str() - Philippe Mathieu-Daudé

From: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
To: qemu-devel@nongnu.org
Cc: "Luc Michel" <luc@lmichel.fr>,
	"Eduardo Habkost" <ehabkost@redhat.com>,
	"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
	"Alistair Francis" <alistair.francis@wdc.com>,
	"Richard Henderson" <rth@twiddle.net>
Subject: [PATCH] util/cutils: Silent Coverity array overrun warning in freq_to_str()
Date: Thu, 29 Oct 2020 19:55:06 +0100	[thread overview]
Message-ID: <20201029185506.1241912-1-f4bug@amsat.org> (raw)

The biggest input value freq_to_str() can accept is UINT64_MAX,
which is ~18.446 EHz, less than 1000 EHz.
Add an assertion to help Coverity.

This silents CID 1435957:  Memory - illegal accesses (OVERRUN):

>>> Overrunning array "suffixes" of 7 8-byte elements at element
    index 7 (byte offset 63) using index "idx" (which evaluates to 7).

Reported-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 util/cutils.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/util/cutils.c b/util/cutils.c
index c395974fab4..69c0ad7f888 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -891,6 +891,7 @@ char *freq_to_str(uint64_t freq_hz)
     double freq = freq_hz;
     size_t idx = 0;
 
+    assert(freq <= UINT64_MAX); /* Max 64-bit value is less than 1000 EHz */
     while (freq >= 1000.0 && idx < ARRAY_SIZE(suffixes)) {
         freq /= 1000.0;
         idx++;
-- 
2.26.2


