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netem: Annotate struct disttable with __counted_by

PATCH Applied Kees Cook 4 participants 4 messages Oct 3, 2023 – Oct 6, 2023

Subsystems (4)
Networking Network drivers Traffic control (tc) Netem network emulator
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Kees Cook

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#0 lore raw

PATCH 1/1 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(-)
net/sched/sch_netem.c +1 -1
index 4ad39a4a3cf5..6ba2dc191ed9 100644
@@ -67,7 +67,7 @@
 
 struct disttable {
 	u32  size;
-	s16 table[];
+	s16 table[] __counted_by(size);
 };
 
 struct netem_sched_data {
Signature · 1 line
2.34.1
Reviewed-by on v1 1/1
#1 lore raw
Quoted 8 lines · Kees Cook

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.

Quoted 11 lines
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

Quoted 17 lines
---
  net/sched/sch_netem.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)
net/sched/sch_netem.c +1 -1
index 4ad39a4a3cf5..6ba2dc191ed9 100644
@@ -67,7 +67,7 @@
 
  struct disttable {
  	u32  size;
-	s16 table[];
+	s16 table[] __counted_by(size);
  };
 
  struct netem_sched_data {
maintainer Reviewed-by on v1 1/1
#2 lore raw
In reply to Kees Cook
Quoted 8 lines · 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.

Quoted 11 lines
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[].

CI Applied
#3 lore raw
In reply to Kees Cook
This patch was applied to netdev/net-next.git (main) by Jakub Kicinski <[email protected]>:

Hello:

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

Quoted 9 lines · 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!

Signature · 2 lines
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