[Qemu-devel] [PATCH v4] inet_listen_opts: add error checking

[Qemu-devel] [PATCH v4] inet_listen_opts: add error checking

[Gerd Hoffmann]

Don't use atoi() function which doesn't detect errors, switch to
strtol and error out on failures.  Also add a range check while
being at it.

[ v4: didn't commit buildfix.  -ENOCOFFEE.  sorry for the spam ]
[ v3: oops, v2 didn't build ]
[ v2: use parse_uint_full instead of strtol ]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 util/qemu-sockets.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
index 6b97dc1..13590de 100644
--- a/util/qemu-sockets.c
+++ b/util/qemu-sockets.c
@@ -133,8 +133,18 @@ int inet_listen_opts(QemuOpts *opts, int port_offset, Error **errp)
         ai.ai_family = PF_INET6;
 
     /* lookup */
-    if (port_offset)
-        snprintf(port, sizeof(port), "%d", atoi(port) + port_offset);
+    if (port_offset) {
+        unsigned long long baseport;
+        if (parse_uint_full(port, &baseport, 10) < 0) {
+            error_setg(errp, "can't convert to a number: %s", port);
+            return -1;
+        }
+        if (baseport + port_offset > 65535) {
+            error_setg(errp, "port %s out of range", port);
+            return -1;
+        }
+        snprintf(port, sizeof(port), "%d", (int)baseport + port_offset);
+    }
     rc = getaddrinfo(strlen(addr) ? addr : NULL, port, &ai, &res);
     if (rc != 0) {
         error_setg(errp, "address resolution failed for %s:%s: %s", addr, port,
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH v4] inet_listen_opts: add error checking

[Eric Blake]

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On 12/13/2013 03:12 AM, Gerd Hoffmann wrote:
> Don't use atoi() function which doesn't detect errors, switch to
> strtol and error out on failures.  Also add a range check while
> being at it.
> 
> [ v4: didn't commit buildfix.  -ENOCOFFEE.  sorry for the spam ]
> [ v3: oops, v2 didn't build ]
> [ v2: use parse_uint_full instead of strtol ]

Patch changelog belongs...

> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---

...here.  You can add a '---' separator in your commit message (and thus
have two '---' lines in 'git send-email' output), if you still want to
track the changelog in your commits (but remember to hoist your S-o-B
when doing that).

>  util/qemu-sockets.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 

> +    if (port_offset) {
> +        unsigned long long baseport;
> +        if (parse_uint_full(port, &baseport, 10) < 0) {
> +            error_setg(errp, "can't convert to a number: %s", port);
> +            return -1;
> +        }
> +        if (baseport + port_offset > 65535) {
> +            error_setg(errp, "port %s out of range", port);

error_setg() is still reporting on a bogus errno value at this point.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v4] inet_listen_opts: add error checking

[Eric Blake]

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On 12/13/2013 05:42 AM, Eric Blake wrote:
> On 12/13/2013 03:12 AM, Gerd Hoffmann wrote:
>> Don't use atoi() function which doesn't detect errors, switch to
>> strtol and error out on failures.  Also add a range check while
>> being at it.
>>
>> [ v4: didn't commit buildfix.  -ENOCOFFEE.  sorry for the spam ]
>> [ v3: oops, v2 didn't build ]
>> [ v2: use parse_uint_full instead of strtol ]
> 

> 
>> +    if (port_offset) {
>> +        unsigned long long baseport;
>> +        if (parse_uint_full(port, &baseport, 10) < 0) {
>> +            error_setg(errp, "can't convert to a number: %s", port);
>> +            return -1;
>> +        }
>> +        if (baseport + port_offset > 65535) {
>> +            error_setg(errp, "port %s out of range", port);
> 
> error_setg() is still reporting on a bogus errno value at this point.

My bad, now it's my turn for early-morning confusion.

I was thinking of error_setg_errno, but you are using error_setg.

That said, you STILL have a problem:

> +        if (baseport + port_offset > 65535) {

If baseport is 0xfffffffffffffffe, and port_offset is 5000, then their
sum is 4998 which is not > 65535, so you fall through:

> +            error_setg(errp, "port %s out of range", port);
> +            return -1;
> +        }
> +        snprintf(port, sizeof(port), "%d", (int)baseport + port_offset);

and happily use a value that is less than port_offset at this point.  I
don't think you meant to do that.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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