2015-08-14 00:36:06

by Adrien Schildknecht

Subject: [PATCH] iwlwifi: out-of-bounds access in iwl_init_sband_channels

Both loops of this function compare data from the 'chan' array and then
check if the index is valid.

The 2 conditions should be inverted to avoid an out-of-bounds access.

Signed-off-by: Adrien Schildknecht <[email protected]>
---
drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c b/drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c
index 21302b6..acc3d18 100644
--- a/drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c
+++ b/drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c
@@ -713,12 +713,12 @@ int iwl_init_sband_channels(struct iwl_nvm_data *data,
struct ieee80211_channel *chan = &data->channels[0];
int n = 0, idx = 0;

- while (chan->band != band && idx < n_channels)
+ while (idx < n_channels && chan->band != band)
chan = &data->channels[++idx];

sband->channels = &data->channels[idx];

- while (chan->band == band && idx < n_channels) {
+ while (idx < n_channels && chan->band == band) {
chan = &data->channels[++idx];
n++;
}
--
2.5.0

2015-08-14 04:32:05

by Grumbach, Emmanuel

Subject: Re: [PATCH] iwlwifi: out-of-bounds access in iwl_init_sband_channels

Hi,

On 08/14/2015 03:36 AM, Adrien Schildknecht wrote:
> Both loops of this function compare data from the 'chan' array and then
> check if the index is valid.
>
> The 2 conditions should be inverted to avoid an out-of-bounds access.
>

Was that found by a static analyzer or any other automated tool, or was
that the result of your very careful review?

> Signed-off-by: Adrien Schildknecht <[email protected]>
> ---
> drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c b/drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c
> index 21302b6..acc3d18 100644
> --- a/drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c
> +++ b/drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c
> @@ -713,12 +713,12 @@ int iwl_init_sband_channels(struct iwl_nvm_data *data,
> struct ieee80211_channel *chan = &data->channels[0];
> int n = 0, idx = 0;
>
> - while (chan->band != band && idx < n_channels)
> + while (idx < n_channels && chan->band != band)
> chan = &data->channels[++idx];
>
> sband->channels = &data->channels[idx];
>
> - while (chan->band == band && idx < n_channels) {
> + while (idx < n_channels && chan->band == band) {
> chan = &data->channels[++idx];
> n++;
> }
>

Looks fine - I'll pick it up.

2015-08-14 07:04:20

by Adrien Schildknecht

Subject: Re: [PATCH] iwlwifi: out-of-bounds access in iwl_init_sband_channels

Hi,

> On 08/14/2015 03:36 AM, Adrien Schildknecht wrote:
> > Both loops of this function compare data from the 'chan' array and
> > then check if the index is valid.
> >
> > The 2 conditions should be inverted to avoid an out-of-bounds
> > access.
> >
>
> Was that found by a static analyzer or any other automated tool, or
> was that the result of your very careful review?

The error has been reported by KASan:
==================================================================
BUG: KASan: out of bounds access in iwl_init_sband_channels+0x207/0x260 [iwlwifi] at addr ffff8800c2d0aac8
Read of size 4 by task modprobe/329
==================================================================

--
Adrien Schildknecht

2015-08-14 07:14:34

by Kalle Valo

Subject: Re: [PATCH] iwlwifi: out-of-bounds access in iwl_init_sband_channels

Adrien Schildknecht <[email protected]> writes:

> Hi,
>
>> On 08/14/2015 03:36 AM, Adrien Schildknecht wrote:
>> > Both loops of this function compare data from the 'chan' array and
>> > then check if the index is valid.
>> >
>> > The 2 conditions should be inverted to avoid an out-of-bounds
>> > access.
>> >
>>
>> Was that found by a static analyzer or any other automated tool, or
>> was that the result of your very careful review?
>
> The error has been reported by KASan:
> ==================================================================
> BUG: KASan: out of bounds access in iwl_init_sband_channels+0x207/0x260 [iwlwifi] at addr ffff8800c2d0aac8
> Read of size 4 by task modprobe/329
> ==================================================================

Always try to add information like this to the commit log, it's very
useful.

--
Kalle Valo

2015-08-14 09:06:06

by Adrien Schildknecht

Subject: [PATCH v2] iwlwifi: out-of-bounds access in iwl_init_sband_channels

KASan error report:
==================================================================
BUG: KASan: out of bounds access in iwl_init_sband_channels+0x207/0x260 [iwlwifi] at addr ffff8800c2d0aac8
Read of size 4 by task modprobe/329
==================================================================

Both loops of this function compare data from the 'chan' array and then
check if the index is valid.

The 2 conditions should be inverted to avoid an out-of-bounds access.

Signed-off-by: Adrien Schildknecht <[email protected]>
---
drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c b/drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c
index 21302b6..acc3d18 100644
--- a/drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c
+++ b/drivers/net/wireless/iwlwifi/iwl-eeprom-parse.c
@@ -713,12 +713,12 @@ int iwl_init_sband_channels(struct iwl_nvm_data *data,
struct ieee80211_channel *chan = &data->channels[0];
int n = 0, idx = 0;

- while (chan->band != band && idx < n_channels)
+ while (idx < n_channels && chan->band != band)
chan = &data->channels[++idx];

sband->channels = &data->channels[idx];

- while (chan->band == band && idx < n_channels) {
+ while (idx < n_channels && chan->band == band) {
chan = &data->channels[++idx];
n++;
}
--
2.5.0