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Commit 4d26d1d1 authored by David Herrmann's avatar David Herrmann Committed by Jiri Kosina
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Revert "HID: uhid: use strlcpy() instead of strncpy()" 



This reverts commit 336fd4f5.

Please note that `strlcpy()` does *NOT* do what you think it does.
strlcpy() *ALWAYS* reads the full input string, regardless of the
'length' parameter. That is, if the input is not zero-terminated,
strlcpy() will *READ* beyond input boundaries. It does this, because it
always returns the size it *would* copy if the target was big enough,
not the truncated size it actually copied.

The original code was perfectly fine. The hid device is
zero-initialized and the strncpy() functions copied up to n-1
characters. The result is always zero-terminated this way.

This is the third time someone tried to replace strncpy with strlcpy in
this function, and gets it wrong. I now added a comment that should at
least make people reconsider.

Signed-off-by: default avatarDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 8c01db76

drivers/hid/uhid.c

+7 −6
Original line number Diff line number Diff line
@@ -497,12 +497,13 @@ static int uhid_dev_create2(struct uhid_device *uhid, 
		goto err_free;

	}



	len = min(sizeof(hid->name), sizeof(ev->u.create2.name));

	strlcpy(hid->name, ev->u.create2.name, len);

	len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys));

	strlcpy(hid->phys, ev->u.create2.phys, len);

	len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq));

	strlcpy(hid->uniq, ev->u.create2.uniq, len);

	/* @hid is zero-initialized, strncpy() is correct, strlcpy() not */

	len = min(sizeof(hid->name), sizeof(ev->u.create2.name)) - 1;

	strncpy(hid->name, ev->u.create2.name, len);

	len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys)) - 1;

	strncpy(hid->phys, ev->u.create2.phys, len);

	len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq)) - 1;

	strncpy(hid->uniq, ev->u.create2.uniq, len);



	hid->ll_driver = &uhid_hid_driver;

	hid->bus = ev->u.create2.bus;