From bd25c8066fc2e0868228b3cb0563d6c1b65505b2 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Tue, 19 May 2020 18:30:18 -0500 Subject: RDMA/siw: Replace one-element array and use struct_size() helper The current codebase makes use of one-element arrays in the following form: struct something { int length; u8 data[1]; }; struct something *instance; instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL); instance->length = size; memcpy(instance->data, source, size); but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. So, replace the one-element array with a flexible-array member. Also, make use of the new struct_size() helper to properly calculate the size of struct siw_pbl. This issue was found with the help of Coccinelle and, audited and fixed _manually_. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Link: https://lore.kernel.org/r/20200519233018.GA6105@embeddedor Signed-off-by: Gustavo A. R. Silva Signed-off-by: Jason Gunthorpe --- drivers/infiniband/sw/siw/siw.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/infiniband/sw/siw/siw.h') diff --git a/drivers/infiniband/sw/siw/siw.h b/drivers/infiniband/sw/siw/siw.h index af5e9f8c0fcd..5a58a1cc7a7e 100644 --- a/drivers/infiniband/sw/siw/siw.h +++ b/drivers/infiniband/sw/siw/siw.h @@ -139,7 +139,7 @@ struct siw_pble { struct siw_pbl { unsigned int num_buf; unsigned int max_buf; - struct siw_pble pbe[1]; + struct siw_pble pbe[]; }; /* -- cgit v1.2.3