diff mbox series

[08/14] net: ipa: Annotate struct ipa_power with __counted_by

Message ID 20230922172858.3822653-8-keescook@chromium.org
State New
Headers
Series Batch 1: Annotate structs with __counted_by |

Commit Message

Kees Cook Sept. 22, 2023, 5:28 p.m. UTC 
  Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct ipa_power.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Alex Elder <elder@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/net/ipa/ipa_power.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Gustavo A. R. Silva Sept. 23, 2023, 1:55 a.m. UTC | #1 
On 9/22/23 11:28, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> As found with Coccinelle[1], add __counted_by for struct ipa_power.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Alex Elder <elder@kernel.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
Alex Elder Sept. 23, 2023, 12:09 p.m. UTC | #2 
On 9/22/23 12:28 PM, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> As found with Coccinelle[1], add __counted_by for struct ipa_power.

Looks good, thanks.

Reviewed-by: Alex Elder <elder@linaro.org>

Note that there is some interaction between struct ipa_power_data
and struct ipa_power (the former is used to initialize the latter).
Both of these contain flexible arrays counted by another field in
the structure.  It seems possible that the way these are initialized
might need slight modification to allow the compiler to do its
enforcement; if that's the case, please reach out to me.

					-Alex


> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Alex Elder <elder@kernel.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>   drivers/net/ipa/ipa_power.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ipa/ipa_power.c b/drivers/net/ipa/ipa_power.c
> index 0eaa7a7f3343..e223886123ce 100644
> --- a/drivers/net/ipa/ipa_power.c
> +++ b/drivers/net/ipa/ipa_power.c
> @@ -67,7 +67,7 @@ struct ipa_power {
>   	spinlock_t spinlock;	/* used with STOPPED/STARTED power flags */
>   	DECLARE_BITMAP(flags, IPA_POWER_FLAG_COUNT);
>   	u32 interconnect_count;
> -	struct icc_bulk_data interconnect[];
> +	struct icc_bulk_data interconnect[] __counted_by(interconnect_count);
>   };
>   
>   /* Initialize interconnects required for IPA operation */
Kees Cook Sept. 24, 2023, 2:03 a.m. UTC | #3 
On Sat, Sep 23, 2023 at 07:09:19AM -0500, Alex Elder wrote:
> On 9/22/23 12:28 PM, Kees Cook wrote:
> > Prepare for the coming implementation by GCC and Clang of the __counted_by
> > attribute. Flexible array members annotated with __counted_by can have
> > their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> > (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> > functions).
> > 
> > As found with Coccinelle[1], add __counted_by for struct ipa_power.
> 
> Looks good, thanks.
> 
> Reviewed-by: Alex Elder <elder@linaro.org>
> 
> Note that there is some interaction between struct ipa_power_data
> and struct ipa_power (the former is used to initialize the latter).
> Both of these contain flexible arrays counted by another field in
> the structure.  It seems possible that the way these are initialized
> might need slight modification to allow the compiler to do its
> enforcement; if that's the case, please reach out to me.

I think it's all okay:

struct ipa_power_data {
        u32 core_clock_rate;
        u32 interconnect_count;         /* # entries in interconnect_data[] */
        const struct ipa_interconnect_data *interconnect_data;
};

"interconnect_data" here is a pointer, not a flexible array. (Yes,
__counted_by is expected to be expanded in the future for pointers,
but not yet.) Looking at initializers, I didn't see any problems with
how struct ipa_power is allocated.

Thanks for the heads-up; I'm sure I'll look at this again when we can
further expand __counted_by to pointers. :)

-Kees
diff mbox series

Patch

diff --git a/drivers/net/ipa/ipa_power.c b/drivers/net/ipa/ipa_power.c
index 0eaa7a7f3343..e223886123ce 100644
--- a/drivers/net/ipa/ipa_power.c
+++ b/drivers/net/ipa/ipa_power.c
@@ -67,7 +67,7 @@  struct ipa_power {
 	spinlock_t spinlock;	/* used with STOPPED/STARTED power flags */
 	DECLARE_BITMAP(flags, IPA_POWER_FLAG_COUNT);
 	u32 interconnect_count;
-	struct icc_bulk_data interconnect[];
+	struct icc_bulk_data interconnect[] __counted_by(interconnect_count);
 };
 
 /* Initialize interconnects required for IPA operation */