Re: 2.6.37-rc7: Regression: b43: crashes in hwrng_register()

Larry Finger
2010-12-31T00:46:33Z

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On 12/30/2010 06:37 PM, Herbert Xu wrote:
> On Thu, Dec 30, 2010 at 04:49:05PM -0600, Larry Finger wrote:
>>
>> Do you see any problems in the code in drivers/net/wireless/b43/main.c or
>> drivers/char/hw_random/via-rng.c. As the latter seems to make b43 fail, I am
>> suspecting via-rng, but I have no proof.
>
> My suspicion is that VIA's xstore is writing more than 4 bytes as
> the list pointer happens to lie immediately after rng->priv which
> is where xstore is writing to.
>
> Harald, do you know whether this is documented or is this a known
> errata item?

The following patch should be able to test if xstore is overwriting the list
pointer.

Larry
---

Index: wireless-testing/include/linux/hw_random.h
===================================================================
--- wireless-testing.orig/include/linux/hw_random.h
+++ wireless-testing/include/linux/hw_random.h
@@ -38,6 +38,7 @@ struct hwrng {
int (*data_read)(struct hwrng *rng, u32 *data);
int (*read)(struct hwrng *rng, void *data, size_t max, bool wait);
unsigned long priv;
+ char junk[12];

/* internal. */
struct list_head list;

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Index: wireless-testing/include/linux/hw_random.h
===================================================================
--- wireless-testing.orig/include/linux/hw_random.h
+++ wireless-testing/include/linux/hw_random.h
@@ -38,6 +38,7 @@ struct hwrng {
int (*data_read)(struct hwrng *rng, u32 *data);
int (*read)(struct hwrng *rng, void *data, size_t max, bool wait);
unsigned long priv;
+ char junk[12];

/* internal. */
struct list_head list;