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From d70b74d6f893947aa22d3f14df10f92a8c349388 Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Thu, 8 Mar 2018 10:33:16 +0100
Subject: [PATCH] readwrite: make sure excess reads don't go beyond buffer end
CVE-2018-1000122
Bug: https://curl.haxx.se/docs/adv_2018-b047.html
Detected by OSS-fuzz
---
lib/transfer.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/lib/transfer.c
+++ b/lib/transfer.c
@@ -791,10 +791,15 @@ static CURLcode readwrite_data(struct Cu
} /* if(!header and data to read) */
- if(conn->handler->readwrite &&
- (excess > 0 && !conn->bits.stream_was_rewound)) {
+ if(conn->handler->readwrite && excess && !conn->bits.stream_was_rewound) {
/* Parse the excess data */
k->str += nread;
+
+ if(&k->str[excess] > &k->buf[data->set.buffer_size]) {
+ /* the excess amount was too excessive(!), make sure
+ it doesn't read out of buffer */
+ excess = &k->buf[data->set.buffer_size] - k->str;
+ }
nread = (ssize_t)excess;
result = conn->handler->readwrite(data, conn, &nread, &readmore);
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