Am 22.05.20 um 03:25 schrieb Gustavo A. R. Silva:
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 NISLANDS_SMC_SWSTATE. This issue was found with the help of Coccinelle and, audited and fixed _manually_. [1] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgcc.gnu.org%2Fonlinedocs%2Fgcc%2FZero-Length.html&data=02%7C01%7Cchristian.koenig%40amd.com%7C7dd54e944eff4d17178008d7fdee62d7%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637257072615411745&sdata=fQHnbXZpsgiMjHOr%2By0Uq12jpCYEYbdX5K26iNkwyeM%3D&reserved=0 [2] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FKSPP%2Flinux%2Fissues%2F21&data=02%7C01%7Cchristian.koenig%40amd.com%7C7dd54e944eff4d17178008d7fdee62d7%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637257072615411745&sdata=gg20YupmqsaW%2Bg3VyJL%2BkjE3kFwnWF1RD1D2QP04OLk%3D&reserved=0 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <[email protected]> --- drivers/gpu/drm/amd/amdgpu/si_dpm.h | 2 +- drivers/gpu/drm/radeon/ni_dpm.c | 7 ++++--- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/si_dpm.h b/drivers/gpu/drm/amd/amdgpu/si_dpm.h index 6b7d292b919f3..bc0be6818e218 100644 --- a/drivers/gpu/drm/amd/amdgpu/si_dpm.h +++ b/drivers/gpu/drm/amd/amdgpu/si_dpm.h @@ -781,7 +781,7 @@ struct NISLANDS_SMC_SWSTATE uint8_t levelCount; uint8_t padding2; uint8_t padding3; - NISLANDS_SMC_HW_PERFORMANCE_LEVEL levels[1]; + NISLANDS_SMC_HW_PERFORMANCE_LEVEL levels[]; };typedef struct NISLANDS_SMC_SWSTATE NISLANDS_SMC_SWSTATE;diff --git a/drivers/gpu/drm/radeon/ni_dpm.c b/drivers/gpu/drm/radeon/ni_dpm.c index b57c37ddd164c..7d81dde509dc9 100644 --- a/drivers/gpu/drm/radeon/ni_dpm.c +++ b/drivers/gpu/drm/radeon/ni_dpm.c @@ -2685,11 +2685,12 @@ static int ni_upload_sw_state(struct radeon_device *rdev, struct rv7xx_power_info *pi = rv770_get_pi(rdev); u16 address = pi->state_table_start + offsetof(NISLANDS_SMC_STATETABLE, driverState); - u16 state_size = sizeof(NISLANDS_SMC_SWSTATE) + - ((NISLANDS_MAX_SMC_PERFORMANCE_LEVELS_PER_SWSTATE - 1) * sizeof(NISLANDS_SMC_HW_PERFORMANCE_LEVEL)); + NISLANDS_SMC_SWSTATE *smc_state; + u16 state_size = struct_size(smc_state, levels, + NISLANDS_MAX_SMC_PERFORMANCE_LEVELS_PER_SWSTATE);
Probably better to use size_t instead of u16 here. With that fixed feel free to stick my rb on the patch.
Regards, Christian.
int ret; - NISLANDS_SMC_SWSTATE *smc_state = kzalloc(state_size, GFP_KERNEL);+ smc_state = kzalloc(state_size, GFP_KERNEL);if (smc_state == NULL) return -ENOMEM;
