From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org,
Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>,
Christophe Lombard <christophe_lombard@fr.ibm.com>,
Philippe Bergheaud <philippe.bergheaud@fr.ibm.com>
Cc: Andrew Donnellan <andrew.donnellan@au1.ibm.com>,
Alastair D'Silva <alastair@linux.ibm.com>,
Vaibhav Jain <vaibhav@linux.vnet.ibm.com>,
Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Subject: Re: [v4] powerpc: Avoid signed to unsigned conversion in set_thread_tidr()
Date: Wed, 29 Nov 2017 23:06:44 +1100 (AEDT) [thread overview]
Message-ID: <3ymzm473ltz9t2Z@ozlabs.org> (raw)
In-Reply-To: <20171128025304.30574-1-vaibhav@linux.vnet.ibm.com>
On Tue, 2017-11-28 at 02:53:04 UTC, Vaibhav Jain wrote:
> There is an unsafe signed to unsigned conversion in set_thread_tidr()
> that may cause an error value to be assigned to SPRN_TIDR register and
> used as thread-id.
>
> The issue happens as assign_thread_tidr() returns an int and
> thread.tidr is an unsigned-long. So a negative error code returned
> from assign_thread_tidr() will fail the error check and gets assigned
> as tidr as a large positive value.
>
> To fix this the patch assigns the return value of assign_thread_tidr()
> to a temporary int and assigns it to thread.tidr iff its '> 0'.
>
> The patch shouldn't impact the calling convention of set_thread_tidr()
> i.e all -ve return-values are error codes and a return value of '0'
> indicates success.
>
> Fixes: ec233ede4c86("powerpc: Add support for setting SPRN_TIDR")
> Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
> Reviewed-by: Christophe Lombard clombard@linux.vnet.ibm.com
Applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/aca7573fde95152378361cba734996
cheers
prev parent reply other threads:[~2017-11-29 12:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-28 2:53 [PATCH v4] powerpc: Avoid signed to unsigned conversion in set_thread_tidr() Vaibhav Jain
2017-11-28 8:26 ` christophe lombard
2017-11-29 12:06 ` Michael Ellerman [this message]
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