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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo...@kernel.org>
---
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 246bb9ac557d8..c9cfe90a29471 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 {
--
2.26.2
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