| Message ID | 20210916163311.11968-1-andrew.shadura@collabora.co.uk (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Jiri Kosina |
| Headers | show |
| Series | HID: u2fzero: ignore incomplete packets without data | expand |
Hi again, On 16/09/2021 17:33, Andrej Shadura wrote: > Since the actual_length calculation is performed unsigned, packets > shorter than 7 bytes (e.g. packets without data or otherwise truncated) > or non-received packets ("zero" bytes) can cause buffer overflow. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=214437 > Fixes: 42337b9d4d958("HID: add driver for U2F Zero built-in LED and RNG") > Signed-off-by: Andrej Shadura <andrew.shadura@collabora.co.uk> Having sent the email I realised I forgot to describe the actual situation when I ran into this bug. It happened after I inserted and removed the device multiple times very quickly. I know it’s not extremely reliable way to reproduce it, and it rarely happened to me before for some reason, but on the current kernel (5.11.0) I was able to cause the crash every time I tried.
On Thu, 16 Sep 2021, Andrej Shadura wrote: > Since the actual_length calculation is performed unsigned, packets > shorter than 7 bytes (e.g. packets without data or otherwise truncated) > or non-received packets ("zero" bytes) can cause buffer overflow. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=214437 > Fixes: 42337b9d4d958("HID: add driver for U2F Zero built-in LED and RNG") > Signed-off-by: Andrej Shadura <andrew.shadura@collabora.co.uk> > --- > drivers/hid/hid-u2fzero.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/hid/hid-u2fzero.c b/drivers/hid/hid-u2fzero.c > index 95e0807878c7..d70cd3d7f583 100644 > --- a/drivers/hid/hid-u2fzero.c > +++ b/drivers/hid/hid-u2fzero.c > @@ -198,7 +198,9 @@ static int u2fzero_rng_read(struct hwrng *rng, void *data, > } > > ret = u2fzero_recv(dev, &req, &resp); > - if (ret < 0) > + > + /* ignore errors or packets without data */ > + if (ret < offsetof(struct u2f_hid_msg, init.data)) > return 0; > Applied, thanks.
diff --git a/drivers/hid/hid-u2fzero.c b/drivers/hid/hid-u2fzero.c index 95e0807878c7..d70cd3d7f583 100644 --- a/drivers/hid/hid-u2fzero.c +++ b/drivers/hid/hid-u2fzero.c @@ -198,7 +198,9 @@ static int u2fzero_rng_read(struct hwrng *rng, void *data, } ret = u2fzero_recv(dev, &req, &resp); - if (ret < 0) + + /* ignore errors or packets without data */ + if (ret < offsetof(struct u2f_hid_msg, init.data)) return 0; /* only take the minimum amount of data it is safe to take */
Since the actual_length calculation is performed unsigned, packets shorter than 7 bytes (e.g. packets without data or otherwise truncated) or non-received packets ("zero" bytes) can cause buffer overflow. Link: https://bugzilla.kernel.org/show_bug.cgi?id=214437 Fixes: 42337b9d4d958("HID: add driver for U2F Zero built-in LED and RNG") Signed-off-by: Andrej Shadura <andrew.shadura@collabora.co.uk> --- drivers/hid/hid-u2fzero.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)