2023-10-03 23:19:59

by Kees Cook

Subject: [PATCH] netem: Annotate struct disttable with __counted_by

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 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 disttable.

Cc: Stephen Hemminger <[email protected]>
Cc: Jamal Hadi Salim <[email protected]>
Cc: Cong Wang <[email protected]>
Cc: Jiri Pirko <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: [email protected]
Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1]
Signed-off-by: Kees Cook <[email protected]>
---
net/sched/sch_netem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 4ad39a4a3cf5..6ba2dc191ed9 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -67,7 +67,7 @@

struct disttable {
u32 size;
- s16 table[];
+ s16 table[] __counted_by(size);
};

struct netem_sched_data {
--
2.34.1

2023-10-03 23:38:47

by Gustavo A. R. Silva

Subject: Re: [PATCH] netem: Annotate struct disttable with __counted_by

On 10/4/23 01:18, 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 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 disttable.
>
> Cc: Stephen Hemminger <[email protected]>
> Cc: Jamal Hadi Salim <[email protected]>
> Cc: Cong Wang <[email protected]>
> Cc: Jiri Pirko <[email protected]>
> Cc: "David S. Miller" <[email protected]>
> Cc: Eric Dumazet <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: Paolo Abeni <[email protected]>
> Cc: [email protected]
> Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1]
> Signed-off-by: Kees Cook <[email protected]>

Reviewed-by: Gustavo A. R. Silva <[email protected]>

Thanks
--
Gustavo

> ---
> net/sched/sch_netem.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
> index 4ad39a4a3cf5..6ba2dc191ed9 100644
> --- a/net/sched/sch_netem.c
> +++ b/net/sched/sch_netem.c
> @@ -67,7 +67,7 @@
>
> struct disttable {
> u32 size;
> - s16 table[];
> + s16 table[] __counted_by(size);
> };
>
> struct netem_sched_data {

2023-10-04 03:32:58

by Stephen Hemminger

Subject: Re: [PATCH] netem: Annotate struct disttable with __counted_by

On Tue, 3 Oct 2023 16:18:23 -0700
Kees Cook <[email protected]> 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 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 disttable.
>
> Cc: Stephen Hemminger <[email protected]>
> Cc: Jamal Hadi Salim <[email protected]>
> Cc: Cong Wang <[email protected]>
> Cc: Jiri Pirko <[email protected]>
> Cc: "David S. Miller" <[email protected]>
> Cc: Eric Dumazet <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: Paolo Abeni <[email protected]>
> Cc: [email protected]
> Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1]
> Signed-off-by: Kees Cook <[email protected]

Reviewed-by: Stephen Hemminger <[email protected]>

PS: size is intended wrong in original code but that is not important.
Should have lined up with table[].

2023-10-06 01:41:05

by patchwork-bot+netdevbpf

Subject: Re: [PATCH] netem: Annotate struct disttable with __counted_by

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <[email protected]>:

On Tue, 3 Oct 2023 16:18:23 -0700 you 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 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 disttable.
>
> [...]

Here is the summary with links:
- netem: Annotate struct disttable with __counted_by
https://git.kernel.org/netdev/net-next/c/0fef0907d6fa

You are awesome, thank you!
--
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