This is an effort to get rid of all multiplications from allocation
functions in order to prevent integer overflows [1][2].
As the "box" variable is a pointer to "struct intel_uncore_box" and
this structure ends in a flexible array:
struct intel_uncore_box {
[...]
struct intel_uncore_extra_reg shared_regs[];
};
the preferred way in the kernel is to use the struct_size() helper to
do the arithmetic instead of the calculation "size + count * size" in
the kzalloc_node() function.
This way, the code is more readable and safer.
This code was detected with the help of Coccinelle, and audited and
modified manually.
Link:
https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
[1]
Link: https://github.com/KSPP/linux/issues/160 [2]
Signed-off-by: Erick Archer <erick.arc...@outlook.com>
---
Hi,
The Coccinelle script used to detect this code pattern is the following:
virtual report
@rule1@
type t1;
type t2;
identifier i0;
identifier i1;
identifier i2;
identifier ALLOC =~
"kmalloc|kzalloc|kmalloc_node|kzalloc_node|vmalloc|vzalloc|kvmalloc|kvzalloc";
position p1;
@@
i0 = sizeof(t1) + sizeof(t2) * i1;
...
i2 = ALLOC@p1(..., i0, ...);
@script:python depends on report@
p1 << rule1.p1;
@@
msg = "WARNING: verify allocation on line %s" % (p1[0].line)
coccilib.report.print_report(p1[0],msg)
Regards,
Erick
---
arch/x86/events/intel/uncore.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 258e2cdf28fa..ce756d24c370 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -350,12 +350,11 @@ static void uncore_pmu_init_hrtimer(struct
intel_uncore_box *box)
static struct intel_uncore_box *uncore_alloc_box(struct intel_uncore_type
*type,
int node)
{
- int i, size, numshared = type->num_shared_regs ;
+ int i, numshared = type->num_shared_regs;
struct intel_uncore_box *box;
- size = sizeof(*box) + numshared * sizeof(struct intel_uncore_extra_reg);
-
- box = kzalloc_node(size, GFP_KERNEL, node);
+ box = kzalloc_node(struct_size(box, shared_regs, numshared), GFP_KERNEL,
+ node);
if (!box)
return NULL;
--
2.25.1
