[PATCH 1/2] xenstat: fix unsigned less-than-0 comparison

[PATCH 1/2] xenstat: fix unsigned less-than-0 comparison

[Matthew Daley]

Commit 1438d36f ("xenstat: Fix buffer over-run with new_domains being
negative.") attempted to fix the handling of a negative error result
from xc_domain_getinfolist in xenstat_get_node. However, it forgot to
change the result variable from an unsigned type to a signed one.

Do so, allowing the error result to be handled properly.

Signed-off-by: Matthew Daley <mattd@bugfuzz.com>
---
 tools/xenstat/libxenstat/src/xenstat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/xenstat/libxenstat/src/xenstat.c b/tools/xenstat/libxenstat/src/xenstat.c
index e5facb8..8072a90 100644
--- a/tools/xenstat/libxenstat/src/xenstat.c
+++ b/tools/xenstat/libxenstat/src/xenstat.c
@@ -164,7 +164,7 @@ xenstat_node *xenstat_get_node(xenstat_handle * handle, unsigned int flags)
 	xenstat_node *node;
 	xc_physinfo_t physinfo = { 0 };
 	xc_domaininfo_t domaininfo[DOMAIN_CHUNK_SIZE];
-	unsigned int new_domains;
+	int new_domains;
 	unsigned int i;
 
 	/* Create the node */
-- 
1.9.2

[PATCH 2/2] xenstat: don't leak memory in getBridge

[Matthew Daley]

getBridge's method of returning a result was a little confused:
allocating a result buffer but never using it.

Simplify by instead allowing a result buffer to be passed in and
modifying the single usage to match.

Signed-off-by: Matthew Daley <mattd@bugfuzz.com>
---
 tools/xenstat/libxenstat/src/xenstat_linux.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/tools/xenstat/libxenstat/src/xenstat_linux.c b/tools/xenstat/libxenstat/src/xenstat_linux.c
index 931b24e..24335e1 100644
--- a/tools/xenstat/libxenstat/src/xenstat_linux.c
+++ b/tools/xenstat/libxenstat/src/xenstat_linux.c
@@ -64,14 +64,12 @@ static const char PROCNETDEV_HEADER[] =
 
 /* We need to get the name of the bridge interface for use with bonding interfaces */
 /* Use excludeName parameter to avoid adding bridges we don't care about, eg. virbr0 */
-char *getBridge(char *excludeName)
+void getBridge(char *excludeName, char *result, size_t resultLen)
 {
 	struct dirent *de;
 	DIR *d;
 
-	char tmp[256] = { 0 }, *bridge;
-
-	bridge = (char *)malloc(16 * sizeof(char));
+	char tmp[256] = { 0 };
 
 	d = opendir("/sys/class/net");
 	while ((de = readdir(d)) != NULL) {
@@ -79,14 +77,14 @@ char *getBridge(char *excludeName)
 			&& (strstr(de->d_name, excludeName) == NULL)) {
 				sprintf(tmp, "/sys/class/net/%s/bridge", de->d_name);
 
-				if (access(tmp, F_OK) == 0)
-					bridge = de->d_name;
+				if (access(tmp, F_OK) == 0) {
+					strncpy(result, de->d_name, resultLen - 1);
+					result[resultLen - 1] = 0;
+				}
 		}
 	}
 
 	closedir(d);
-
-	return bridge;
 }
 
 /* parseNetLine provides regular expression based parsing for lines from /proc/net/dev, all the */
@@ -279,7 +277,7 @@ int xenstat_collect_networks(xenstat_node * node)
 	      SEEK_SET);
 
 	/* We get the bridge devices for use with bonding interface to get bonding interface stats */
-	snprintf(devBridge, 16, "%s", getBridge("vir"));
+	getBridge("vir", devBridge, sizeof(devBridge));
 	snprintf(devNoBridge, 16, "p%s", devBridge);
 
 	while (fgets(line, 512, priv->procnetdev)) {
-- 
1.9.2

Re: [PATCH 1/2] xenstat: fix unsigned less-than-0 comparison

[Konrad Rzeszutek Wilk]

On Sun, May 04, 2014 at 08:31:46PM +1200, Matthew Daley wrote:
> Commit 1438d36f ("xenstat: Fix buffer over-run with new_domains being
> negative.") attempted to fix the handling of a negative error result
> from xc_domain_getinfolist in xenstat_get_node. However, it forgot to
> change the result variable from an unsigned type to a signed one.
> 
> Do so, allowing the error result to be handled properly.
> 
> Signed-off-by: Matthew Daley <mattd@bugfuzz.com>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

I was looking at this by changing the underlay libxc calls to
using 'unsigned' instead of 'int' but that has kind of been
preempted.

Thanks for fixing it!
> ---
>  tools/xenstat/libxenstat/src/xenstat.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/xenstat/libxenstat/src/xenstat.c b/tools/xenstat/libxenstat/src/xenstat.c
> index e5facb8..8072a90 100644
> --- a/tools/xenstat/libxenstat/src/xenstat.c
> +++ b/tools/xenstat/libxenstat/src/xenstat.c
> @@ -164,7 +164,7 @@ xenstat_node *xenstat_get_node(xenstat_handle * handle, unsigned int flags)
>  	xenstat_node *node;
>  	xc_physinfo_t physinfo = { 0 };
>  	xc_domaininfo_t domaininfo[DOMAIN_CHUNK_SIZE];
> -	unsigned int new_domains;
> +	int new_domains;
>  	unsigned int i;
>  
>  	/* Create the node */
> -- 
> 1.9.2
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel

Re: [PATCH 1/2] xenstat: fix unsigned less-than-0 comparison

[Ian Campbell]

On Mon, 2014-05-05 at 10:32 -0400, Konrad Rzeszutek Wilk wrote:
> On Sun, May 04, 2014 at 08:31:46PM +1200, Matthew Daley wrote:
> > Commit 1438d36f ("xenstat: Fix buffer over-run with new_domains being
> > negative.") attempted to fix the handling of a negative error result
> > from xc_domain_getinfolist in xenstat_get_node. However, it forgot to
> > change the result variable from an unsigned type to a signed one.
> > 
> > Do so, allowing the error result to be handled properly.
> > 
> > Signed-off-by: Matthew Daley <mattd@bugfuzz.com>
> 
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Acked both + applied, thanks!