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| author | Joel Stanley <joel@jms.id.au> | 2014-04-22 18:36:47 +1000 |
|---|---|---|
| committer | Eli Qiao <taget@linux.vnet.ibm.com> | 2014-04-22 16:55:30 +0800 |
| commit | e8196a55149a30b05e318ba41a3c591c0963473d (patch) | |
| tree | 0c4c6b9c2054e67b8d32447a88e63d63cd4d9e2d | |
| parent | dbb1c98ee186dd6ee5bfe499140a1d8421565a1d (diff) | |
| download | powerkvm-e8196a55149a30b05e318ba41a3c591c0963473d.tar.gz | |
powerpc/powernv: Fix sysparam sysfs error handling
When a sysparam query in OPAL returned a negative value (error code),
sysfs would spew out a decent chunk of memory; almost 64K more than
expected. This was traced to a sign/unsigned mix up in the OPAL sysparam
sysfs code at sys_param_show.
The return value of sys_param_show is a ssize_t, calculated using
return ret ? ret : attr->param_size;
Alan Modra explains:
"attr->param_size" is an unsigned int, "ret" an int, so the overall
expression has type unsigned int. Result is that ret is cast to
unsigned int before being cast to ssize_t.
Instead of using the ternary operator, set ret to the param_size if an
error is not detected. The same bug exists in the sysfs write callback;
this patch fixes it in the same way.
A note on debugging this next time: on my system gcc will warn about
this if compiled with -Wsign-compare, which is not enabled by -Wall,
only -Wextra.
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
| -rw-r--r-- | arch/powerpc/platforms/powernv/opal-sysparam.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/powerpc/platforms/powernv/opal-sysparam.c b/arch/powerpc/platforms/powernv/opal-sysparam.c index 5d6e37f626c46a..6764a7c98346c9 100644 --- a/arch/powerpc/platforms/powernv/opal-sysparam.c +++ b/arch/powerpc/platforms/powernv/opal-sysparam.c @@ -121,9 +121,10 @@ static ssize_t sys_param_show(struct kobject *kobj, memcpy(buf, param_data_buf, attr->param_size); + ret = attr->param_size; out: mutex_unlock(&opal_sysparam_mutex); - return ret ? ret : attr->param_size; + return ret; } static ssize_t sys_param_store(struct kobject *kobj, @@ -138,7 +139,9 @@ static ssize_t sys_param_store(struct kobject *kobj, ret = opal_set_sys_param(attr->param_id, attr->param_size, param_data_buf); mutex_unlock(&opal_sysparam_mutex); - return ret ? ret : count; + if (!ret) + ret = count; + return ret; } void __init opal_sys_param_init(void) |