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 <idryomov@xxxxxxxxx> Cc: Xiubo Li <xiubli@xxxxxxxxxx> Cc: Jeff Layton <jlayton@xxxxxxxxxx> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx> Cc: Eric Dumazet <edumazet@xxxxxxxxxx> Cc: Jakub Kicinski <kuba@xxxxxxxxxx> Cc: Paolo Abeni <pabeni@xxxxxxxxxx> Cc: ceph-devel@xxxxxxxxxxxxxxx Cc: netdev@xxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- 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 = &monc->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
