Re: [Qemu-devel] [PATCH] qdev-properties: Fix (u)intXX parsers
On Wed, May 26, 2010 at 12:28:13PM +0200, Kevin Wolf wrote:
scanf calls must not use PRI constants, they have probably the wrong size and
corrupt memory. We could replace them by SCN ones, but strtol is simpler than
scanf here anyway. While at it, also fix the parsers to reject garbage after
the number (4096xyz was accepted before).
Signed-off-by: Kevin Wolf kw...@redhat.com
---
hw/qdev-properties.c | 50
+++---
1 files changed, 35 insertions(+), 15 deletions(-)
diff --git a/hw/qdev-properties.c b/hw/qdev-properties.c
index 9ffdba7..9a61ca2 100644
--- a/hw/qdev-properties.c
+++ b/hw/qdev-properties.c
@@ -68,12 +68,14 @@ PropertyInfo qdev_prop_bit = {
static int parse_uint8(DeviceState *dev, Property *prop, const char *str)
{
uint8_t *ptr = qdev_get_prop_ptr(dev, prop);
-const char *fmt;
+char *end;
/* accept both hex and decimal */
-fmt = strncasecmp(str, 0x,2) == 0 ? % PRIx8 : % PRIu8;
-if (sscanf(str, fmt, ptr) != 1)
+*ptr = strtoul(str, end, 0);
+if (end != str + strlen(str)) {
return -EINVAL;
+}
I think you can avoid the O(n) operation here in the other cases with
a test like this:
if ((end == str) || (*end != '\0'))
return -EINVAL
Regards,
Daniel
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Re: [Qemu-devel] [PATCH] qdev-properties: Fix (u)intXX parsers
Am 26.05.2010 12:45, schrieb Daniel P. Berrange:
On Wed, May 26, 2010 at 12:28:13PM +0200, Kevin Wolf wrote:
scanf calls must not use PRI constants, they have probably the wrong size and
corrupt memory. We could replace them by SCN ones, but strtol is simpler than
scanf here anyway. While at it, also fix the parsers to reject garbage after
the number (4096xyz was accepted before).
Signed-off-by: Kevin Wolf kw...@redhat.com
---
hw/qdev-properties.c | 50
+++---
1 files changed, 35 insertions(+), 15 deletions(-)
diff --git a/hw/qdev-properties.c b/hw/qdev-properties.c
index 9ffdba7..9a61ca2 100644
--- a/hw/qdev-properties.c
+++ b/hw/qdev-properties.c
@@ -68,12 +68,14 @@ PropertyInfo qdev_prop_bit = {
static int parse_uint8(DeviceState *dev, Property *prop, const char *str)
{
uint8_t *ptr = qdev_get_prop_ptr(dev, prop);
-const char *fmt;
+char *end;
/* accept both hex and decimal */
-fmt = strncasecmp(str, 0x,2) == 0 ? % PRIx8 : % PRIu8;
-if (sscanf(str, fmt, ptr) != 1)
+*ptr = strtoul(str, end, 0);
+if (end != str + strlen(str)) {
return -EINVAL;
+}
I think you can avoid the O(n) operation here in the other cases with
a test like this:
if ((end == str) || (*end != '\0'))
return -EINVAL
It probably doesn't really make a difference here, but you're right.
I'll send another version with this change.
Kevin
Re: [Qemu-devel] [PATCH] qdev-properties: Fix (u)intXX parsers
Kevin Wolf kw...@redhat.com writes: scanf calls must not use PRI constants, they have probably the wrong size and corrupt memory. We could replace them by SCN ones, but strtol is simpler than scanf here anyway. While at it, also fix the parsers to reject garbage after the number (4096xyz was accepted before). Do we have more misuse of PRI with scanf elsewhere? No need to fix them all in one commit (and thus delay this fix); I just want to make sure somebody looks.
Re: [Qemu-devel] [PATCH] qdev-properties: Fix (u)intXX parsers
Am 26.05.2010 13:13, schrieb Markus Armbruster: Kevin Wolf kw...@redhat.com writes: scanf calls must not use PRI constants, they have probably the wrong size and corrupt memory. We could replace them by SCN ones, but strtol is simpler than scanf here anyway. While at it, also fix the parsers to reject garbage after the number (4096xyz was accepted before). Do we have more misuse of PRI with scanf elsewhere? No need to fix them all in one commit (and thus delay this fix); I just want to make sure somebody looks. I saw another one in some Xen file that Gerd should fix some time. I'm not aware of any other. Kevin
