2014-12-10 09:40:05

by Brian Norris

Subject: [PATCH] brcmsmac: don't leak kernel memory via printk()

Debug code prints the fifo name via custom dev_warn() wrappers. The
fifo_names array is only non-zero when debugging is manually enabled,
which is all well and good. However, it's *not* good that this array
uses zero-length arrays in the non-debug case, and so it doesn't
actually have any memory allocated to it. This means that as far as we
know, fifo_names[i] actually points to garbage memory.

I've seen this in my log:

[ 4601.205511] brcmsmac bcma0:1: wl0: brcms_c_d11hdrs_mac80211: �GeL txop exceeded phylen 137/256 dur 1602/1504

So let's give this array space enough to fill it with a NULL byte.

Signed-off-by: Brian Norris <[email protected]>
Cc: Brett Rudley <[email protected]>
Cc: Arend van Spriel <[email protected]>
Cc: "Franky (Zhenhui) Lin" <[email protected]>
Cc: Hante Meuleman <[email protected]>
Cc: "John W. Linville" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
drivers/net/wireless/brcm80211/brcmsmac/main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/brcm80211/brcmsmac/main.c b/drivers/net/wireless/brcm80211/brcmsmac/main.c
index 1b474828d5b8..aed0c948dce8 100644
--- a/drivers/net/wireless/brcm80211/brcmsmac/main.c
+++ b/drivers/net/wireless/brcm80211/brcmsmac/main.c
@@ -316,7 +316,7 @@ static const u16 xmtfifo_sz[][NFIFO] = {
static const char * const fifo_names[] = {
"AC_BK", "AC_BE", "AC_VI", "AC_VO", "BCMC", "ATIM" };
#else
-static const char fifo_names[6][0];
+static const char fifo_names[6][1];
#endif

#ifdef DEBUG
--
2.2.0

2014-12-18 06:32:05

by Brian Norris

Subject: Re: [PATCH] brcmsmac: don't leak kernel memory via printk()

+ others [1]

On Wed, Dec 10, 2014 at 1:39 AM, Brian Norris
<[email protected]> wrote:
> Debug code prints the fifo name via custom dev_warn() wrappers. The
> fifo_names array is only non-zero when debugging is manually enabled,
> which is all well and good. However, it's *not* good that this array
> uses zero-length arrays in the non-debug case, and so it doesn't
> actually have any memory allocated to it. This means that as far as we
> know, fifo_names[i] actually points to garbage memory.
>
> I've seen this in my log:
>
> [ 4601.205511] brcmsmac bcma0:1: wl0: brcms_c_d11hdrs_mac80211: �GeL txop exceeded phylen 137/256 dur 1602/1504
>
> So let's give this array space enough to fill it with a NULL byte.
>
> Signed-off-by: Brian Norris <[email protected]>
> Cc: Brett Rudley <[email protected]>
> Cc: Arend van Spriel <[email protected]>
> Cc: "Franky (Zhenhui) Lin" <[email protected]>
> Cc: Hante Meuleman <[email protected]>
> Cc: "John W. Linville" <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]

BTW, I guess this qualifies as a security hole, albeit a small one.
Should this be CC: [email protected]?

> ---
> drivers/net/wireless/brcm80211/brcmsmac/main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/brcm80211/brcmsmac/main.c b/drivers/net/wireless/brcm80211/brcmsmac/main.c
> index 1b474828d5b8..aed0c948dce8 100644
> --- a/drivers/net/wireless/brcm80211/brcmsmac/main.c
> +++ b/drivers/net/wireless/brcm80211/brcmsmac/main.c
> @@ -316,7 +316,7 @@ static const u16 xmtfifo_sz[][NFIFO] = {
> static const char * const fifo_names[] = {
> "AC_BK", "AC_BE", "AC_VI", "AC_VO", "BCMC", "ATIM" };
> #else
> -static const char fifo_names[6][0];
> +static const char fifo_names[6][1];
> #endif
>
> #ifdef DEBUG

Brian

[1] http://lwn.net/Articles/626689/

2014-12-18 13:01:52

by Arend van Spriel

Subject: Re: [PATCH] brcmsmac: don't leak kernel memory via printk()

On 12/18/14 07:32, Brian Norris wrote:
> + others [1]
>
> On Wed, Dec 10, 2014 at 1:39 AM, Brian Norris
> <[email protected]> wrote:
>> Debug code prints the fifo name via custom dev_warn() wrappers. The
>> fifo_names array is only non-zero when debugging is manually enabled,
>> which is all well and good. However, it's *not* good that this array
>> uses zero-length arrays in the non-debug case, and so it doesn't
>> actually have any memory allocated to it. This means that as far as we
>> know, fifo_names[i] actually points to garbage memory.
>>
>> I've seen this in my log:
>>
>> [ 4601.205511] brcmsmac bcma0:1: wl0: brcms_c_d11hdrs_mac80211: �GeL txop exceeded phylen 137/256 dur 1602/1504
>>
>> So let's give this array space enough to fill it with a NULL byte.
>>
>> Signed-off-by: Brian Norris<[email protected]>
>> Cc: Brett Rudley<[email protected]>
>> Cc: Arend van Spriel<[email protected]>
>> Cc: "Franky (Zhenhui) Lin"<[email protected]>
>> Cc: Hante Meuleman<[email protected]>
>> Cc: "John W. Linville"<[email protected]>
>> Cc: [email protected]
>> Cc: [email protected]
>> Cc: [email protected]
>
> BTW, I guess this qualifies as a security hole, albeit a small one.
> Should this be CC: [email protected]?

I have no strong opinion on this, but I guess. Feel free to do so.

Regards,
Arend

>> ---
>> drivers/net/wireless/brcm80211/brcmsmac/main.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/wireless/brcm80211/brcmsmac/main.c b/drivers/net/wireless/brcm80211/brcmsmac/main.c
>> index 1b474828d5b8..aed0c948dce8 100644
>> --- a/drivers/net/wireless/brcm80211/brcmsmac/main.c
>> +++ b/drivers/net/wireless/brcm80211/brcmsmac/main.c
>> @@ -316,7 +316,7 @@ static const u16 xmtfifo_sz[][NFIFO] = {
>> static const char * const fifo_names[] = {
>> "AC_BK", "AC_BE", "AC_VI", "AC_VO", "BCMC", "ATIM" };
>> #else
>> -static const char fifo_names[6][0];
>> +static const char fifo_names[6][1];
>> #endif
>>
>> #ifdef DEBUG
>
> Brian
>
> [1] http://lwn.net/Articles/626689/

2014-12-10 10:30:24

by Arend van Spriel

Subject: Re: [PATCH] brcmsmac: don't leak kernel memory via printk()

On 10-12-14 10:39, Brian Norris wrote:
> Debug code prints the fifo name via custom dev_warn() wrappers. The
> fifo_names array is only non-zero when debugging is manually enabled,
> which is all well and good. However, it's *not* good that this array
> uses zero-length arrays in the non-debug case, and so it doesn't
> actually have any memory allocated to it. This means that as far as we
> know, fifo_names[i] actually points to garbage memory.
>
> I've seen this in my log:
>
> [ 4601.205511] brcmsmac bcma0:1: wl0: brcms_c_d11hdrs_mac80211: �GeL txop exceeded phylen 137/256 dur 1602/1504
>
> So let's give this array space enough to fill it with a NULL byte.
>

+ Acked-by: Arend van Spriel <[email protected]>
> Signed-off-by: Brian Norris <[email protected]>
> Cc: Brett Rudley <[email protected]>
- Cc: Arend van Spriel <[email protected]>
> Cc: "Franky (Zhenhui) Lin" <[email protected]>
> Cc: Hante Meuleman <[email protected]>
> Cc: "John W. Linville" <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> ---
> drivers/net/wireless/brcm80211/brcmsmac/main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/brcm80211/brcmsmac/main.c b/drivers/net/wireless/brcm80211/brcmsmac/main.c
> index 1b474828d5b8..aed0c948dce8 100644
> --- a/drivers/net/wireless/brcm80211/brcmsmac/main.c
> +++ b/drivers/net/wireless/brcm80211/brcmsmac/main.c
> @@ -316,7 +316,7 @@ static const u16 xmtfifo_sz[][NFIFO] = {
> static const char * const fifo_names[] = {
> "AC_BK", "AC_BE", "AC_VI", "AC_VO", "BCMC", "ATIM" };
> #else
> -static const char fifo_names[6][0];
> +static const char fifo_names[6][1];
> #endif
>
> #ifdef DEBUG
>