From: Bruce Richardson <bruce.richardson@intel.com>
To: dev@dpdk.org
Cc: ciara.power@intel.com, roretzla@linux.microsoft.com,
Bruce Richardson <bruce.richardson@intel.com>
Subject: [PATCH v3 5/5] telemetry: remove VLA in json string format function
Date: Wed, 5 Apr 2023 17:03:26 +0100 [thread overview]
Message-ID: <20230405160326.186921-6-bruce.richardson@intel.com> (raw)
In-Reply-To: <20230405160326.186921-1-bruce.richardson@intel.com>
Since variable length arrays (VLAs) are potentially insecure and
unsupported by some compilers, rework the code to remove their use. As
with previous changes to remove VLAs in the telemetry code, this
function uses two methods to avoid modifying the buffer when adding to
it fails:
* if there are only a few characters in the buffer, save them off to
restore on failure, then use the buffer as-is,
* otherwise use malloc rather than a VLA to allocate a temporary buffer
and copy from that on success only.
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
app/test/test_telemetry_json.c | 2 +-
lib/telemetry/telemetry_json.h | 19 +++++++++++++++++--
2 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/app/test/test_telemetry_json.c b/app/test/test_telemetry_json.c
index e81e3a8a98..5617eac540 100644
--- a/app/test/test_telemetry_json.c
+++ b/app/test/test_telemetry_json.c
@@ -129,7 +129,7 @@ test_string_char_escaping(void)
{
static const char str[] = "A string across\ntwo lines and \"with quotes\"!";
const char *expected = "\"A string across\\ntwo lines and \\\"with quotes\\\"!\"";
- char buf[sizeof(str) + 10];
+ char buf[sizeof(str) + 10] = "";
int used = 0;
used = rte_tel_json_str(buf, sizeof(buf), used, str);
diff --git a/lib/telemetry/telemetry_json.h b/lib/telemetry/telemetry_json.h
index c087b833eb..7999535848 100644
--- a/lib/telemetry/telemetry_json.h
+++ b/lib/telemetry/telemetry_json.h
@@ -134,13 +134,28 @@ __json_format_str_to_buf(char *buf, const int len,
static inline int
__json_format_str(char *buf, const int len, const char *prefix, const char *str, const char *suffix)
{
- char tmp[len];
int ret;
+ char saved[4] = "";
+ char *tmp;
+
+ if (strnlen(buf, sizeof(saved)) < sizeof(saved)) {
+ /* we have only a few bytes in buffer, so save them off to restore on error*/
+ strcpy(saved, buf);
+ ret = __json_format_str_to_buf(buf, len, prefix, str, suffix);
+ if (ret == 0)
+ strcpy(buf, saved); /* restore */
+ return ret;
+ }
+
+ tmp = malloc(len);
+ if (tmp == NULL)
+ return 0;
ret = __json_format_str_to_buf(tmp, len, prefix, str, suffix);
if (ret > 0)
- strcpy(buf, tmp);
+ strcpy(buf, saved);
+ free(tmp);
return ret;
}
--
2.37.2
next prev parent reply other threads:[~2023-04-05 16:05 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-10 18:18 [PATCH] telemetry: fix autotest failures on Alpine Bruce Richardson
2023-03-10 19:08 ` Stephen Hemminger
2023-03-13 9:38 ` Bruce Richardson
2023-04-05 15:44 ` [PATCH v2 0/5] telemetry: remove variable length arrays Bruce Richardson
2023-04-05 15:44 ` [PATCH v2 1/5] telemetry: fix autotest failures on Alpine Bruce Richardson
2023-04-07 19:21 ` Tyler Retzlaff
2023-04-11 8:43 ` Bruce Richardson
2023-04-05 15:44 ` [PATCH v2 2/5] telemetry: remove variable length array in printf fn Bruce Richardson
2023-04-05 15:44 ` [PATCH v2 3/5] telemetry: split out body of json string format fn Bruce Richardson
2023-04-05 15:44 ` [PATCH v2 4/5] telemetry: rename local variables Bruce Richardson
2023-04-05 15:44 ` [PATCH v2 5/5] telemetry: remove VLA in json string format function Bruce Richardson
2023-04-05 16:03 ` [PATCH v3 0/5] telemetry: remove variable length arrays Bruce Richardson
2023-04-05 16:03 ` [PATCH v3 1/5] telemetry: fix autotest failures on Alpine Bruce Richardson
2023-04-07 19:22 ` Tyler Retzlaff
2023-04-05 16:03 ` [PATCH v3 2/5] telemetry: remove variable length array in printf fn Bruce Richardson
2023-04-07 19:25 ` Tyler Retzlaff
2023-04-05 16:03 ` [PATCH v3 3/5] telemetry: split out body of json string format fn Bruce Richardson
2023-04-07 19:28 ` Tyler Retzlaff
2023-04-05 16:03 ` [PATCH v3 4/5] telemetry: rename local variables Bruce Richardson
2023-04-07 19:50 ` Tyler Retzlaff
2023-04-11 8:58 ` Bruce Richardson
2023-04-05 16:03 ` Bruce Richardson [this message]
2023-04-07 19:54 ` [PATCH v3 5/5] telemetry: remove VLA in json string format function Tyler Retzlaff
2023-05-25 7:12 ` David Marchand
2023-05-24 20:47 ` [PATCH v3 0/5] telemetry: remove variable length arrays Thomas Monjalon
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