AcoSail/kernel_optimize_test
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Revert "HID: uhid: use strlcpy() instead of strncpy()"

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This reverts commit 336fd4f5f2.

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: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
David Herrmann 2018-11-14 14:16:42 +01:00 committed by Jiri Kosina
parent 8c01db7619
commit 4d26d1d1e8
1 changed files with 7 additions and 6 deletions
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13
drivers/hid/uhid.c
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@ -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;