| Message ID | 20200519233018.GA6105@embeddedor (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | bd25c8066fc2e0868228b3cb0563d6c1b65505b2 |
| Delegated to: | Jason Gunthorpe |
| Headers | show |
| Series | RDMA/siw: Replace one-element array and use struct_size() helper | expand |
On Tue, May 19, 2020 at 06:30:18PM -0500, Gustavo A. R. Silva wrote: > 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") > > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> > --- > drivers/infiniband/sw/siw/siw.h | 2 +- > drivers/infiniband/sw/siw/siw_mem.c | 5 +---- > 2 files changed, 2 insertions(+), 5 deletions(-) Applied to for-next, thanks Jason
On Tue, May 19, 2020 at 08:52:31PM -0300, Jason Gunthorpe wrote: > > > > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> > > --- > > drivers/infiniband/sw/siw/siw.h | 2 +- > > drivers/infiniband/sw/siw/siw_mem.c | 5 +---- > > 2 files changed, 2 insertions(+), 5 deletions(-) > > Applied to for-next, thanks > Thanks, Jason. -- Gustavo
diff --git a/drivers/infiniband/sw/siw/siw.h b/drivers/infiniband/sw/siw/siw.h index af5e9f8c0fcd0..5a58a1cc7a7e8 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[]; }; /* diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c index e2061dc0b043c..87117781d6374 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);
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") Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- drivers/infiniband/sw/siw/siw.h | 2 +- drivers/infiniband/sw/siw/siw_mem.c | 5 +---- 2 files changed, 2 insertions(+), 5 deletions(-)