From ede403ea405f74fec1c065b4b24f65a645d7027f Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Tue, 19 May 2020 17:55:45 -0500 Subject: [PATCH] drm/amdgpu/smu10: Replace one-element array and use struct_size() helper MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 smu10_voltage_dependency_table. 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 80c49dd975f4 ("cxgb3/l2t: Fix undefined behaviour") Acked-by: Christian König Signed-off-by: Gustavo A. R. Silva Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c | 6 ++---- drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h | 2 +- 2 files changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c index 4f8c1b85e6882..d1f0cc77d4603 100644 --- a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c +++ b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c @@ -410,12 +410,10 @@ static int smu10_get_clock_voltage_dependency_table(struct pp_hwmgr *hwmgr, struct smu10_voltage_dependency_table **pptable, uint32_t num_entry, const DpmClock_t *pclk_dependency_table) { - uint32_t table_size, i; + uint32_t i; struct smu10_voltage_dependency_table *ptable; - table_size = sizeof(uint32_t) + sizeof(struct smu10_voltage_dependency_table) * num_entry; - ptable = kzalloc(table_size, GFP_KERNEL); - + ptable = kzalloc(struct_size(ptable, entries, num_entry), GFP_KERNEL); if (NULL == ptable) return -ENOMEM; diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h index 1fb296a996f3a..0f969de10fabc 100644 --- a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h +++ b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h @@ -192,7 +192,7 @@ struct smu10_clock_voltage_dependency_record { struct smu10_voltage_dependency_table { uint32_t count; - struct smu10_clock_voltage_dependency_record entries[1]; + struct smu10_clock_voltage_dependency_record entries[]; }; struct smu10_clock_voltage_information { -- 2.39.5