Re: [PATCH v2] iio: core: use kstrdup_const/kfree_const for buffer attributes
From: Jonathan Cameron
Date: Sat Feb 27 2021 - 12:56:15 EST
On 2021年2月23日 09:29:26 +0200
Alexandru Ardelean <ardeleanalex@xxxxxxxxx> wrote:
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When the buffer attributes were wrapped in iio_dev_attr types, I forgot to
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duplicate the names, so that when iio_free_chan_devattr_list() gets called
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on cleanup, these get free'd.
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I stumbled over this while accidentally breaking a driver doing
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iio_device_register(), and then the issue appeared.
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Some ways to fix this are:
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1. Just use kstrdup() during iio_buffer_wrap_attr()
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2. Just use kfree_const() during iio_free_chan_devattr_list
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3. Use both kstrdup_const() & kfree_const() (in the places mentioned above)
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This implements the third option, as it allows some users/drivers to
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specify some attributes allocated on the heap.
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Fixes: a1a11142f66c ("iio: buffer: wrap all buffer attributes into iio_dev_attr")
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Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx>
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---
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drivers/iio/industrialio-buffer.c | 1 +
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drivers/iio/industrialio-core.c | 2 +-
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2 files changed, 2 insertions(+), 1 deletion(-)
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diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
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index 5d641f8adfbd..ac882e60c419 100644
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--- a/drivers/iio/industrialio-buffer.c
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+++ b/drivers/iio/industrialio-buffer.c
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@@ -1306,6 +1306,7 @@ static struct attribute *iio_buffer_wrap_attr(struct iio_buffer *buffer,
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return NULL;
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iio_attr->buffer = buffer;
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+ iio_attr->dev_attr.attr.name = kstrdup_const(attr->name, GFP_KERNEL);
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memcpy(&iio_attr->dev_attr, dattr, sizeof(iio_attr->dev_attr));
Doesn't this wipe out the duplicated string? I swapped the two lines above
which I think should avoid that.
Merged into original patch
Jonathan
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list_add(&iio_attr->l, &buffer->buffer_attr_list);
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diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
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index 0d8c6e88d993..cb2735d2ae4b 100644
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--- a/drivers/iio/industrialio-core.c
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+++ b/drivers/iio/industrialio-core.c
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@@ -1358,7 +1358,7 @@ void iio_free_chan_devattr_list(struct list_head *attr_list)
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struct iio_dev_attr *p, *n;
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list_for_each_entry_safe(p, n, attr_list, l) {
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- kfree(p->dev_attr.attr.name);
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+ kfree_const(p->dev_attr.attr.name);
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list_del(&p->l);
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kfree(p);
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}