Search Linux Wireless

Re: [v4] Fix to avoid IS_ERR_VALUE and IS_ERR abuses on 64bit systems.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On Wednesday 03 August 2016 01:27 AM, Scott Wood wrote:
On 08/02/2016 10:34 AM, arvind Yadav wrote:

On Tuesday 02 August 2016 01:15 PM, Arnd Bergmann wrote:
On Monday, August 1, 2016 4:55:43 PM CEST Scott Wood wrote:
On 08/01/2016 02:02 AM, Arnd Bergmann wrote:
diff --git a/include/linux/err.h b/include/linux/err.h
index 1e35588..c2a2789 100644
--- a/include/linux/err.h
+++ b/include/linux/err.h
@@ -18,7 +18,17 @@
#ifndef __ASSEMBLY__ -#define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
+#define IS_ERR_VALUE(x) unlikely(is_error_check(x))
+
+static inline int is_error_check(unsigned long error)
Please leave the existing macro alone. I think you were looking for
something specific to the return code of qe_muram_alloc() function,
so please add a helper in that subsystem if you need it, not in
the generic header files.
qe_muram_alloc (a.k.a. cpm_muram_alloc) returns unsigned long.  The
problem is certain callers that store the return value in a u32.  Why
not just fix those callers to store it in unsigned long (at least until
error checking is done)?

Yes, that would also address another problem with code like

          kfree((void *)ugeth->tx_bd_ring_offset[i]);

which is not 64-bit safe when tx_bd_ring_offset is a 32-bit value
that also holds the return value of qe_muram_alloc.
Well, hopefully it doesn't hold a return of qe_muram_alloc() when it's
being passed to kfree()...

There's also the code that casts kmalloc()'s return to u32, etc.
ucc_geth is not 64-bit clean in general.

	Arnd
Yes, we will fix caller. Caller api is not safe on 64bit.
The API is fine (or at least, I haven't seen a valid issue pointed out
yet).  The problem is the ucc_geth driver.

Even qe_muram_addr(a.k.a. cpm_muram_addr )passing value unsigned int,
but it should be unsigned long.
cpm_muram_addr takes unsigned long as a parameter, not that it matters
since you can't pass errors into it and a muram offset should never
exceed 32 bits.

-Scott
Yes, It will work for 32bit machine. But will not safe for 64bit.

Example :
ugeth->tx_bd_ring_offset[j] =
    qe_muram_alloc(length  UCC_GETH_TX_BD_RING_ALIGNMENT);
if (!IS_ERR_VALUE(ugeth->tx_bd_ring_offset[j]))
   ugeth->p_tx_bd_ring[j] =
   (u8 __iomem *) qe_muram_addr(ugeth-> tx_bd_ring_offset[j]);

If qe_muram_alloc will return any error,  IS_ERR_VALUE will
always return 0 (IS_ERR_VALUE will always pass for 'unsigned int').
Now qe_muram_addr will return wrong virtual address. Which
can cause an error.

-Arvind

--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux Host AP]     [ATH6KL]     [Linux Wireless Personal Area Network]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [Linux Kernel]     [IDE]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite Hiking]     [MIPS Linux]     [ARM Linux]     [Linux RAID]

  Powered by Linux