| Message ID | 20171024052823.jpetpk2bfazfvfah@dtor-ws (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Oct 24, 2017 at 7:28 AM, Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote: > parse_hid_report_descriptor() has a while (i < length) loop, which > only guarantees that there's at least 1 byte in the buffer, but the > loop body can read multiple bytes which causes out-of-bounds access. > > Reported-by: Andrey Konovalov <andreyknvl@google.com> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> > --- > drivers/input/tablet/gtco.c | 24 +++++++++++++++++------- > 1 file changed, 17 insertions(+), 7 deletions(-) > > diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c > index b796e891e2ee..0351203b8c24 100644 > --- a/drivers/input/tablet/gtco.c > +++ b/drivers/input/tablet/gtco.c > @@ -230,13 +230,24 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report, > > /* Walk this report and pull out the info we need */ > while (i < length) { > - prefix = report[i]; > - > - /* Skip over prefix */ > - i++; > + prefix = report[i++]; > > /* Determine data size and save the data in the proper variable */ > - size = PREF_SIZE(prefix); > + if (PREF_SIZE(prefix) < 1) { AFAIU PREF_SIZE(prefix) == 0 is a perfectly valid item data size. > + dev_err(ddev, > + "Invalid size %d in element at offset %d\n", > + PREF_SIZE(prefix), i); > + break; > + } > + > + size = 1U << (PREF_SIZE(prefix) - 1); This formula doesn't work with PREF_SIZE(prefix) == 0. > + if (i + size >= length) { > + dev_err(ddev, > + "Not enough data (need %d, have %d)\n", > + i + size, length); > + break; > + } > + > switch (size) { > case 1: > data = report[i]; > @@ -244,8 +255,7 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report, > case 2: > data16 = get_unaligned_le16(&report[i]); > break; > - case 3: > - size = 4; > + case 4: > data32 = get_unaligned_le32(&report[i]); > break; > } > -- > 2.15.0.rc0.271.g36b669edcc-goog > > > -- > Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c index b796e891e2ee..0351203b8c24 100644 --- a/drivers/input/tablet/gtco.c +++ b/drivers/input/tablet/gtco.c @@ -230,13 +230,24 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report, /* Walk this report and pull out the info we need */ while (i < length) { - prefix = report[i]; - - /* Skip over prefix */ - i++; + prefix = report[i++]; /* Determine data size and save the data in the proper variable */ - size = PREF_SIZE(prefix); + if (PREF_SIZE(prefix) < 1) { + dev_err(ddev, + "Invalid size %d in element at offset %d\n", + PREF_SIZE(prefix), i); + break; + } + + size = 1U << (PREF_SIZE(prefix) - 1); + if (i + size >= length) { + dev_err(ddev, + "Not enough data (need %d, have %d)\n", + i + size, length); + break; + } + switch (size) { case 1: data = report[i]; @@ -244,8 +255,7 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report, case 2: data16 = get_unaligned_le16(&report[i]); break; - case 3: - size = 4; + case 4: data32 = get_unaligned_le32(&report[i]); break; }
parse_hid_report_descriptor() has a while (i < length) loop, which only guarantees that there's at least 1 byte in the buffer, but the loop body can read multiple bytes which causes out-of-bounds access. Reported-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> --- drivers/input/tablet/gtco.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-)