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| author | David Herrmann <dh.herrmann@gmail.com> | 2018-11-14 16:16:42 +0300 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2018-11-19 16:32:27 +0300 |
| commit | 4d26d1d1e8065bb3326a7c06d5d4698e581443a9 (patch) | |
| tree | f1a9ff9487e6984b11310d08d43f37c207ee7b66 /drivers/hid | |
| parent | 8c01db7619f07c85c5cd81ec5eb83608b56c88f5 (diff) | |
| download | linux-4d26d1d1e8065bb3326a7c06d5d4698e581443a9.tar.xz | |
Revert "HID: uhid: use strlcpy() instead of strncpy()"
This reverts commit 336fd4f5f25157e9e8bd50e898a1bbcd99eaea46.
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>
Diffstat (limited to 'drivers/hid')
| -rw-r--r-- | drivers/hid/uhid.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c index 051639c09f72..840634e0f1e3 100644 --- a/drivers/hid/uhid.c +++ b/drivers/hid/uhid.c @@ -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; |