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mqtt: when Curl_xfer_recv returns error, don't use nread

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A returned error code makes other return value unreliable, and in this
case potentially uninitialized. On error, do not read other return
values like the nread counter.

Spotted by CodeSonar

Closes #13418
This commit is contained in:
Daniel Stenberg 2024-04-19 09:32:23 +02:00
parent b2523fc439
commit 123d3ef5db
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GPG Key ID: 5CC908FDB71E12C2
1 changed files with 2 additions and 2 deletions
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4
lib/mqtt.c
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@ -777,12 +777,12 @@ static CURLcode mqtt_doing(struct Curl_easy *data, bool *done)
case MQTT_REMAINING_LENGTH:
do {
result = Curl_xfer_recv(data, (char *)&byte, 1, &nread);
if(!nread)
if(result || !nread)
break;
Curl_debug(data, CURLINFO_HEADER_IN, (char *)&byte, 1);
mq->pkt_hd[mq->npacket++] = byte;
} while((byte & 0x80) && (mq->npacket < 4));
if(nread && (byte & 0x80))
if(!result && nread && (byte & 0x80))
/* MQTT supports up to 127 * 128^0 + 127 * 128^1 + 127 * 128^2 +
127 * 128^3 bytes. server tried to send more */
result = CURLE_WEIRD_SERVER_REPLY;