[Qemu-devel] [PATCH] block/curl: Improve type safety of s->timeout.

["Richard W.M. Jones" <rjones@redhat.com>]

qemu_opt_get_number returns a uint64_t, and curl_easy_setopt expects a
long (not an int).

Store the timeout (which is a positive number of seconds) as a
uint64_t.  Check that the number given by the user is reasonable.
Cast it to long before calling curl_easy_setopt.

Example error message after this change has been applied:

$ ./qemu-img create -f qcow2 /tmp/test.qcow2 \
    -b 'json: { "file.driver":"https",
                "file.url":"https://foo/bar",
                "file.timeout":-1 }'
qemu-img: /tmp/test.qcow2: Could not open 'json: { "file.driver":"https", "file.url":"https://foo/bar", "file.timeout":-1 }': timeout parameter is too large or negative: Invalid argument

Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
---
 block/curl.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/block/curl.c b/block/curl.c
index 225407c..5233ff6 100644
--- a/block/curl.c
+++ b/block/curl.c
@@ -112,7 +112,7 @@ typedef struct BDRVCURLState {
     char *url;
     size_t readahead_size;
     bool sslverify;
-    int timeout;
+    uint64_t timeout;
     char *cookie;
     bool accept_range;
     AioContext *aio_context;
@@ -390,7 +390,7 @@ static CURLState *curl_init_state(BlockDriverState *bs, BDRVCURLState *s)
         if (s->cookie) {
             curl_easy_setopt(state->curl, CURLOPT_COOKIE, s->cookie);
         }
-        curl_easy_setopt(state->curl, CURLOPT_TIMEOUT, s->timeout);
+        curl_easy_setopt(state->curl, CURLOPT_TIMEOUT, (long)s->timeout);
         curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION,
                          (void *)curl_read_cb);
         curl_easy_setopt(state->curl, CURLOPT_WRITEDATA, (void *)state);
@@ -546,6 +546,10 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags,
 
     s->timeout = qemu_opt_get_number(opts, CURL_BLOCK_OPT_TIMEOUT,
                                      CURL_TIMEOUT_DEFAULT);
+    if (s->timeout > 100000) {
+        error_setg(errp, "timeout parameter is too large or negative");
+        goto out_noclean;
+    }
 
     s->sslverify = qemu_opt_get_bool(opts, CURL_BLOCK_OPT_SSLVERIFY, true);
 
-- 
2.0.4