[Qemu-devel] [PATCH v3] inet_listen_opts: add error checking

[Qemu-devel] [PATCH v3] 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.

[ 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..c3560c1 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) {
+        int baseport;
+        if (parse_uint_full(port, &baseport, 10) < 0) {
+            error_setg(errp, "can't convert to a number: %s", port);
+            return -1;
+        }
+        if (baseport < 0 || baseport + port_offset > 65535) {
+            error_setg(errp, "port %s out of range", port);
+            return -1;
+        }
+        snprintf(port, sizeof(port), "%d", 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 v3] inet_listen_opts: add error checking

[Eric Blake]

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On 12/13/2013 03:08 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.
> 
> [ 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, so that 'git am' will strip it (it's useful for reviewers on
list, but not in 'git log', where you no longer have access to v1 or v2).

>  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..c3560c1 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) {
> +        int baseport;
> +        if (parse_uint_full(port, &baseport, 10) < 0) {

parse_uint_full takes an 'unsigned long long *', but you are passing an
'int *'.  I'm surprised it compiled for you.  It causes a buffer
overflow if the pointer is assigned to, and gives different results
depending on platform endianness.

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

But errno is not set to a sane value at this point, so error_setg() is
wrong.

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


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Re: [Qemu-devel] [PATCH v3] inet_listen_opts: add error checking

[Gerd Hoffmann]

  Hi,

> parse_uint_full takes an 'unsigned long long *', but you are passing an
> 'int *'.  I'm surprised it compiled for you.  It causes a buffer
> overflow if the pointer is assigned to, and gives different results
> depending on platform endianness.

Fixed in v4.

> > +            error_setg(errp, "can't convert to a number: %s", port);
> > +            return -1;
> > +        }
> > +        if (baseport < 0 || baseport + port_offset > 65535) {
> > +            error_setg(errp, "port %s out of range", port);
> 
> But errno is not set to a sane value at this point, so error_setg() is
> wrong.

That would be true for error_setg_errno()-

cheers,
  Gerd