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SubjectRe: EDAC: Fix memory leak in creating CSROW object
On Fri, Apr 19, 2019 at 02:45:16AM +0200, Borislav Petkov wrote:
> On Fri, Apr 19, 2019 at 08:35:36AM +0800, PanBian wrote:
> > Yes, I see that. Because the loop start with (--i), there is no put
> > operation for the device that fails to create. So, I think we cannot
> > rule out the possibility of memory leak.
>
> Ok, so this is not something you trigger - you're basically staring at
> the code?
>
> Well, there's something else questionable in that code which I asked
> Greg about today but we didn't finish that conversation, let me CC him.
>
> So AFAIU, devices for which device_add() has returned success,
> should be removed with their counterpart device_del().
> edac_create_csrow_objects(), however, does put_device() on those in the
> "unwinding" loop.
>
> And for the case where device_add() fails, you should do put_device() to
> it. I.e., what you're saying.
>
> So I think we need to figure what needs to be done when before fixing
> this properly.
>
> Greg?

How about this patch, I think it fixes up everything you need to do
here, right?


diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c
index 464174685589..0fb2d1de6d0e 100644
--- a/drivers/edac/edac_mc_sysfs.c
+++ b/drivers/edac/edac_mc_sysfs.c
@@ -404,6 +404,8 @@ static inline int nr_pages_per_csrow(struct csrow_info *csrow)
static int edac_create_csrow_object(struct mem_ctl_info *mci,
struct csrow_info *csrow, int index)
{
+ int retval;
+
csrow->dev.type = &csrow_attr_type;
csrow->dev.groups = csrow_dev_groups;
device_initialize(&csrow->dev);
@@ -415,7 +417,10 @@ static int edac_create_csrow_object(struct mem_ctl_info *mci,
edac_dbg(0, "creating (virtual) csrow node %s\n",
dev_name(&csrow->dev));

- return device_add(&csrow->dev);
+ retval = device_add(&csrow->dev);
+ if (retval)
+ put_device(&csrow->dev);
+ return retval;
}

/* Create a CSROW object under specifed edac_mc_device */
@@ -649,6 +654,8 @@ static int edac_create_dimm_object(struct mem_ctl_info *mci,

edac_dbg(0, "creating rank/dimm device %s\n", dev_name(&dimm->dev));

+ if (err)
+ put_device(&dimm->dev);
return err;
}

@@ -928,6 +935,7 @@ int edac_create_sysfs_mci_device(struct mem_ctl_info *mci,
err = device_add(&mci->dev);
if (err < 0) {
edac_dbg(1, "failure: create device %s\n", dev_name(&mci->dev));
+ put_device(mci->dev);
goto out;
}

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