Re: [PATCH v2 2/5] target/ppc: powerpc_excp: Add excp_vectors bounds check

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Dec 29, 2021 at 01:57:48PM -0300, Fabiano Rosas wrote:
> The next patch will start accessing the excp_vectors array earlier in
> the function, so add a bounds check as first thing here.
> 
> This converts the empty return on POWERPC_EXCP_NONE to an error. This
> exception number never reaches this function and if it does it
> probably means something else went wrong up the line.
> 
> Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  target/ppc/excp_helper.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index 8b9c6bc5a8..9a03e4b896 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -300,6 +300,10 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
>      target_ulong msr, new_msr, vector;
>      int srr0, srr1, lev = -1;
>  
> +    if (excp <= POWERPC_EXCP_NONE || excp >= POWERPC_EXCP_NB) {
> +        cpu_abort(cs, "Invalid PowerPC exception %d. Aborting\n", excp);
> +    }
> +
>      qemu_log_mask(CPU_LOG_INT, "Raise exception at " TARGET_FMT_lx
>                    " => %08x (%02x)\n", env->nip, excp, env->error_code);
>  
> @@ -353,9 +357,6 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
>  #endif
>  
>      switch (excp) {
> -    case POWERPC_EXCP_NONE:
> -        /* Should never happen */
> -        return;
>      case POWERPC_EXCP_CRITICAL:    /* Critical input                         */
>          switch (excp_model) {
>          case POWERPC_EXCP_40x:

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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