Re: [PATCH] [PATCH] powerpc/vio: use strcpy in modalias_show
On 10/17/2013 08:22 AM, David Laight wrote:
>> Commit e82b89a6f19bae73fb064d1b3dd91fcefbb478f4 used strcat instead of
>> strcpy which can result in an overflow of newlines on the buffer.
> ...
>> --- a/arch/powerpc/kernel/vio.c
>> +++ b/arch/powerpc/kernel/vio.c
>> @@ -1531,12 +1531,12 @@ static ssize_t modalias_show(struct device *dev,
>> struct device_attribute
>> *attr,
>>
>> dn = dev->of_node;
>> if (!dn) {
>> -strcat(buf, "\n");
>> +strcpy(buf, "\n");
>> return strlen(buf);
>> }
>> cp = of_get_property(dn, "compatible", NULL);
>> if (!cp) {
>> -strcat(buf, "\n");
>> +strcpy(buf, "\n");
>> return strlen(buf);
>> }
>
> Why not just:
> buf[0] = '\n';
> buf[1] = 0;
> return 1;
>
> The assignment to buf[1] might not even be needed.
Sure, I guess that'd work too. But it really seems like 1/2 a dozen of one and
six of the other. I'll defer to the preference of the maintainers to see what
they want.
P.
>
> David
>
>
>
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[PATCH] [PATCH] powerpc/vio: use strcpy in modalias_show
Commit e82b89a6f19bae73fb064d1b3dd91fcefbb478f4 used strcat instead of
strcpy which can result in an overflow of newlines on the buffer.
Signed-off-by: Prarit Bhargava
Cc: b...@kernel.crashing.org
Cc: b...@decadent.org.uk
Cc: sta...@vger.kernel.org
---
arch/powerpc/kernel/vio.c |4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/vio.c b/arch/powerpc/kernel/vio.c
index d38cc08..cb92d82 100644
--- a/arch/powerpc/kernel/vio.c
+++ b/arch/powerpc/kernel/vio.c
@@ -1531,12 +1531,12 @@ static ssize_t modalias_show(struct device *dev, struct
device_attribute *attr,
dn = dev->of_node;
if (!dn) {
- strcat(buf, "\n");
+ strcpy(buf, "\n");
return strlen(buf);
}
cp = of_get_property(dn, "compatible", NULL);
if (!cp) {
- strcat(buf, "\n");
+ strcpy(buf, "\n");
return strlen(buf);
}
--
1.7.9.3
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Re: [PATCH] powerpc/vio: Fix modalias_show return values
On 10/16/2013 11:53 PM, Ben Hutchings wrote:
> Commit e82b89a6f19bae73fb064d1b3dd91fcefbb478f4 introduces a trivial
> local denial of service.
>
>> --- a/arch/powerpc/kernel/vio.c
>> +++ b/arch/powerpc/kernel/vio.c
>> @@ -1351,11 +1351,15 @@ static ssize_t modalias_show(struct devi
>> const char *cp;
>>
>> dn = dev->of_node;
>> -if (!dn)
>> -return -ENODEV;
>> +if (!dn) {
>> +strcat(buf, "\n");
>
> Every read from the same sysfs file handle uses the same buffer, which
> gets zero-initialised just once. So if I open the file, read it and
> seek back to 0 repeatedly, I can make modalias_show() write arbitrary
> numbers of newlines into *and beyond* that page-sized buffer.
>
> Obviously strcat() should be strcpy().
>
D'oh! Of course -- I wasn't thinking clearly about that. I'll send out a new
patch.
P.
> Ben.
>
>> +return strlen(buf);
>> +}
>> cp = of_get_property(dn, "compatible", NULL);
>> -if (!cp)
>> -return -ENODEV;
>> +if (!cp) {
>> +strcat(buf, "\n");
>> +return strlen(buf);
>> +}
>>
>> return sprintf(buf, "vio:T%sS%s\n", vio_dev->type, cp);
>> }
>
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[PATCH] ppc, vio fix modalias_show return values
[2nd try at this ... 1st one seems to have gone AWOL]
modalias_show() should return an empty string on error, not -ENODEV.
This causes the following false and annoying error:
> find /sys/devices -name modalias -print0 | xargs -0 cat >/dev/null
cat: /sys/devices/vio/4000/modalias: No such device
cat: /sys/devices/vio/4001/modalias: No such device
cat: /sys/devices/vio/4002/modalias: No such device
cat: /sys/devices/vio/4004/modalias: No such device
cat: /sys/devices/vio/modalias: No such device
Signed-off-by: Prarit Bhargava
Cc: Paul Mackerras
Cc: Steve Best
---
arch/powerpc/kernel/vio.c | 12
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/vio.c b/arch/powerpc/kernel/vio.c
index 78a3506..d38cc08 100644
--- a/arch/powerpc/kernel/vio.c
+++ b/arch/powerpc/kernel/vio.c
@@ -1530,11 +1530,15 @@ static ssize_t modalias_show(struct device *dev, struct
device_attribute *attr,
const char *cp;
dn = dev->of_node;
- if (!dn)
- return -ENODEV;
+ if (!dn) {
+ strcat(buf, "\n");
+ return strlen(buf);
+ }
cp = of_get_property(dn, "compatible", NULL);
- if (!cp)
- return -ENODEV;
+ if (!cp) {
+ strcat(buf, "\n");
+ return strlen(buf);
+ }
return sprintf(buf, "vio:T%sS%s\n", vio_dev->type, cp);
}
--
1.7.9.3
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[PATCH] ppc, vio fix modalias_show return values
modalias_show() should return an empty string on error, not -ENODEV.
This causes the following false and annoying error:
> find /sys/devices -name modalias -print0 | xargs -0 cat >/dev/null
cat: /sys/devices/vio/4000/modalias: No such device
cat: /sys/devices/vio/4001/modalias: No such device
cat: /sys/devices/vio/4002/modalias: No such device
cat: /sys/devices/vio/4004/modalias: No such device
cat: /sys/devices/vio/modalias: No such device
Signed-off-by: Prarit Bhargava
---
arch/powerpc/kernel/vio.c | 12
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/vio.c b/arch/powerpc/kernel/vio.c
index 78a3506..d38cc08 100644
--- a/arch/powerpc/kernel/vio.c
+++ b/arch/powerpc/kernel/vio.c
@@ -1530,11 +1530,15 @@ static ssize_t modalias_show(struct device *dev, struct
device_attribute *attr,
const char *cp;
dn = dev->of_node;
- if (!dn)
- return -ENODEV;
+ if (!dn) {
+ strcat(buf, "\n");
+ return strlen(buf);
+ }
cp = of_get_property(dn, "compatible", NULL);
- if (!cp)
- return -ENODEV;
+ if (!cp) {
+ strcat(buf, "\n");
+ return strlen(buf);
+ }
return sprintf(buf, "vio:T%sS%s\n", vio_dev->type, cp);
}
--
1.7.9.3
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[PATCH]: ppc: notifier_from_errno() cleanup
Minor cleanup of notifier_from_errno() in powerpc.
notifier_from_errno() now contains the if(ret)/else conditional. There is no
need to do it in the powerpc code.
Signed-off-by: Prarit Bhargava
diff --git a/arch/powerpc/platforms/pseries/cmm.c
b/arch/powerpc/platforms/pseries/cmm.c
index f480386..3cafc30 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -508,12 +508,7 @@ static int cmm_memory_isolate_cb(struct notifier_block
*self,
if (action == MEM_ISOLATE_COUNT)
ret = cmm_count_pages(arg);
- if (ret)
- ret = notifier_from_errno(ret);
- else
- ret = NOTIFY_OK;
-
- return ret;
+ return notifier_from_errno(ret);
}
static struct notifier_block cmm_mem_isolate_nb = {
@@ -635,12 +630,7 @@ static int cmm_memory_cb(struct notifier_block *self,
break;
}
- if (ret)
- ret = notifier_from_errno(ret);
- else
- ret = NOTIFY_OK;
-
- return ret;
+ return notifier_from_errno(ret);
}
static struct notifier_block cmm_mem_nb = {
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