* [PATCH] Input: gtco - fix potential out-of-bound access
@ 2017-10-24 5:28 Dmitry Torokhov
2017-10-24 11:04 ` Andrey Konovalov
0 siblings, 1 reply; 5+ messages in thread
From: Dmitry Torokhov @ 2017-10-24 5:28 UTC (permalink / raw)
To: linux-input; +Cc: Andrey Konovalov, linux-kernel
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) {
+ 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;
}
--
2.15.0.rc0.271.g36b669edcc-goog
--
Dmitry
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] Input: gtco - fix potential out-of-bound access
2017-10-24 5:28 [PATCH] Input: gtco - fix potential out-of-bound access Dmitry Torokhov
@ 2017-10-24 11:04 ` Andrey Konovalov
2017-10-24 16:39 ` Dmitry Torokhov
0 siblings, 1 reply; 5+ messages in thread
From: Andrey Konovalov @ 2017-10-24 11:04 UTC (permalink / raw)
To: Dmitry Torokhov; +Cc: linux-input, LKML
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
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] Input: gtco - fix potential out-of-bound access
2017-10-24 11:04 ` Andrey Konovalov
@ 2017-10-24 16:39 ` Dmitry Torokhov
2017-10-25 10:33 ` Andrey Konovalov
0 siblings, 1 reply; 5+ messages in thread
From: Dmitry Torokhov @ 2017-10-24 16:39 UTC (permalink / raw)
To: Andrey Konovalov; +Cc: linux-input, LKML
On Tue, Oct 24, 2017 at 01:04:03PM +0200, Andrey Konovalov wrote:
> 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.
Fair enough. How about the below instead then?
--
Dmitry
Input: gtco - fix potential out-of-bound access
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
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 | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c
index b796e891e2ee..7d8e9fb831c4 100644
--- a/drivers/input/tablet/gtco.c
+++ b/drivers/input/tablet/gtco.c
@@ -230,13 +230,17 @@ 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);
+ size = (1U << PREF_SIZE(prefix)) >> 1;
+ if (size && 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 +248,7 @@ 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;
}
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] Input: gtco - fix potential out-of-bound access
2017-10-24 16:39 ` Dmitry Torokhov
@ 2017-10-25 10:33 ` Andrey Konovalov
2017-10-25 16:10 ` Dmitry Torokhov
0 siblings, 1 reply; 5+ messages in thread
From: Andrey Konovalov @ 2017-10-25 10:33 UTC (permalink / raw)
To: Dmitry Torokhov; +Cc: linux-input, LKML
On Tue, Oct 24, 2017 at 6:39 PM, Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
> On Tue, Oct 24, 2017 at 01:04:03PM +0200, Andrey Konovalov wrote:
>> 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.
>
> Fair enough. How about the below instead then?
>
> --
> Dmitry
>
>
> Input: gtco - fix potential out-of-bound access
>
> From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
>
> 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 | 17 ++++++++++-------
> 1 file changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c
> index b796e891e2ee..7d8e9fb831c4 100644
> --- a/drivers/input/tablet/gtco.c
> +++ b/drivers/input/tablet/gtco.c
> @@ -230,13 +230,17 @@ 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);
> + size = (1U << PREF_SIZE(prefix)) >> 1;
> + if (size && i + size >= length) {
I think this should be >, not >=, as when i + size == length, item
data fits into the remaining space precisely. Also I don't see much
point in checking that size is not 0, but I don't mind it.
> + dev_err(ddev,
> + "Not enough data (need %d, have %d)\n",
> + i + size, length);
> + break;
> + }
> +
> switch (size) {
> case 1:
> data = report[i];
> @@ -244,8 +248,7 @@ 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;
> }
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] Input: gtco - fix potential out-of-bound access
2017-10-25 10:33 ` Andrey Konovalov
@ 2017-10-25 16:10 ` Dmitry Torokhov
0 siblings, 0 replies; 5+ messages in thread
From: Dmitry Torokhov @ 2017-10-25 16:10 UTC (permalink / raw)
To: Andrey Konovalov; +Cc: linux-input, LKML
On Wed, Oct 25, 2017 at 12:33:38PM +0200, Andrey Konovalov wrote:
> On Tue, Oct 24, 2017 at 6:39 PM, Dmitry Torokhov
> <dmitry.torokhov@gmail.com> wrote:
> > On Tue, Oct 24, 2017 at 01:04:03PM +0200, Andrey Konovalov wrote:
> >> 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.
> >
> > Fair enough. How about the below instead then?
> >
> > --
> > Dmitry
> >
> >
> > Input: gtco - fix potential out-of-bound access
> >
> > From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> >
> > 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 | 17 ++++++++++-------
> > 1 file changed, 10 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c
> > index b796e891e2ee..7d8e9fb831c4 100644
> > --- a/drivers/input/tablet/gtco.c
> > +++ b/drivers/input/tablet/gtco.c
> > @@ -230,13 +230,17 @@ 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);
> > + size = (1U << PREF_SIZE(prefix)) >> 1;
> > + if (size && i + size >= length) {
>
> I think this should be >, not >=, as when i + size == length, item
> data fits into the remaining space precisely. Also I don't see much
> point in checking that size is not 0, but I don't mind it.
Yes, you are right, I ma not sure why I thought that condition should be
greater or equal, not simply greater. I'll adjust this and drop the size
!= 0 check as it is definitely not needed with the updated condition.
I'll put you down as reviewed-by.
Thanks!
--
Dmitry
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2017-10-25 16:10 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2017-10-24 5:28 [PATCH] Input: gtco - fix potential out-of-bound access Dmitry Torokhov
2017-10-24 11:04 ` Andrey Konovalov
2017-10-24 16:39 ` Dmitry Torokhov
2017-10-25 10:33 ` Andrey Konovalov
2017-10-25 16:10 ` Dmitry Torokhov
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