Re: [PATCH] ceph: Annotate struct ceph_monmap with __counted_by

2023-09-15 Thread Gustavo A. R. Silva 




On 9/15/23 14:15, 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 ceph_monmap.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.

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

Cc: Ilya Dryomov 
Cc: Xiubo Li 
Cc: Jeff Layton 
Cc: "David S. Miller" 
Cc: Eric Dumazet 
Cc: Jakub Kicinski 
Cc: Paolo Abeni 
Cc: ceph-de...@vger.kernel.org
Cc: net...@vger.kernel.org
Signed-off-by: Kees Cook 


Reviewed-by: Gustavo A. R. Silva 

Thanks
--
Gustavo


---
  include/linux/ceph/mon_client.h | 2 +-
  net/ceph/mon_client.c   | 2 +-
  2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/ceph/mon_client.h b/include/linux/ceph/mon_client.h
index b658961156a0..7a9a40163c0f 100644
--- a/include/linux/ceph/mon_client.h
+++ b/include/linux/ceph/mon_client.h
@@ -19,7 +19,7 @@ struct ceph_monmap {
struct ceph_fsid fsid;
u32 epoch;
u32 num_mon;
-   struct ceph_entity_inst mon_inst[];
+   struct ceph_entity_inst mon_inst[] __counted_by(num_mon);
  };
  
  struct ceph_mon_client;

diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
index faabad6603db..f263f7e91a21 100644
--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -1136,6 +1136,7 @@ static int build_initial_monmap(struct ceph_mon_client 
*monc)
   GFP_KERNEL);
if (!monc->monmap)
return -ENOMEM;
+   monc->monmap->num_mon = num_mon;
  
  	for (i = 0; i < num_mon; i++) {

struct ceph_entity_inst *inst = >monmap->mon_inst[i];
@@ -1147,7 +1148,6 @@ static int build_initial_monmap(struct ceph_mon_client 
*monc)
inst->name.type = CEPH_ENTITY_TYPE_MON;
inst->name.num = cpu_to_le64(i);
}
-   monc->monmap->num_mon = num_mon;
return 0;
  }

[PATCH] ceph: Annotate struct ceph_monmap with __counted_by

2023-09-15 Thread 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 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 ceph_monmap.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.

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

Cc: Ilya Dryomov 
Cc: Xiubo Li 
Cc: Jeff Layton 
Cc: "David S. Miller" 
Cc: Eric Dumazet 
Cc: Jakub Kicinski 
Cc: Paolo Abeni 
Cc: ceph-de...@vger.kernel.org
Cc: net...@vger.kernel.org
Signed-off-by: Kees Cook 
---
 include/linux/ceph/mon_client.h | 2 +-
 net/ceph/mon_client.c   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/ceph/mon_client.h b/include/linux/ceph/mon_client.h
index b658961156a0..7a9a40163c0f 100644
--- a/include/linux/ceph/mon_client.h
+++ b/include/linux/ceph/mon_client.h
@@ -19,7 +19,7 @@ struct ceph_monmap {
struct ceph_fsid fsid;
u32 epoch;
u32 num_mon;
-   struct ceph_entity_inst mon_inst[];
+   struct ceph_entity_inst mon_inst[] __counted_by(num_mon);
 };
 
 struct ceph_mon_client;
diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
index faabad6603db..f263f7e91a21 100644
--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -1136,6 +1136,7 @@ static int build_initial_monmap(struct ceph_mon_client 
*monc)
   GFP_KERNEL);
if (!monc->monmap)
return -ENOMEM;
+   monc->monmap->num_mon = num_mon;
 
for (i = 0; i < num_mon; i++) {
struct ceph_entity_inst *inst = >monmap->mon_inst[i];
@@ -1147,7 +1148,6 @@ static int build_initial_monmap(struct ceph_mon_client 
*monc)
inst->name.type = CEPH_ENTITY_TYPE_MON;
inst->name.num = cpu_to_le64(i);
}
-   monc->monmap->num_mon = num_mon;
return 0;
 }
 
-- 
2.34.1