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_mem.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'drivers/infiniband/sw/siw/siw_mem.c') diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c index e2061dc0b043..87117781d637 100644 --- a/drivers/infiniband/sw/siw/siw_mem.c +++ b/drivers/infiniband/sw/siw/siw_mem.c @@ -349,14 +349,11 @@ dma_addr_t siw_pbl_get_buffer(struct siw_pbl *pbl, u64 off, int *len, int *idx) struct siw_pbl *siw_pbl_alloc(u32 num_buf) { struct siw_pbl *pbl; - int buf_size = sizeof(*pbl); if (num_buf == 0) return ERR_PTR(-EINVAL); - buf_size += ((num_buf - 1) * sizeof(struct siw_pble)); - - pbl = kzalloc(buf_size, GFP_KERNEL); + pbl = kzalloc(struct_size(pbl, pbe, num_buf), GFP_KERNEL); if (!pbl) return ERR_PTR(-ENOMEM); -- cgit v1.2.3-59-g8ed1b