[PATCH v2 1/2] KVM: s390: Improve determination of sizes in kvm_s390_import_bp_data()

SF Markus Elfring
2016-08-24T18:36:26Z

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Wed, 24 Aug 2016 19:45:23 +0200

* A multiplication for the size determination of a memory allocation
indicated that an array data structure should be processed.
Thus reuse the corresponding function "kmalloc_array".

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>

This issue was detected also by using the Coccinelle software.

* Replace the specification of data structures by pointer dereferences
to make the corresponding size determination a bit safer according to
the Linux coding style convention.

* Delete the local variable "size" which became unnecessary with
this refactoring.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---

v2: Rebased on source files from "Linux next-20160824".
Advices were integrated from source code review.

arch/s390/kvm/guestdbg.c | 25 +++++++++++++++----------
1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/arch/s390/kvm/guestdbg.c b/arch/s390/kvm/guestdbg.c
index d1f8241..70b71ac 100644
--- a/arch/s390/kvm/guestdbg.c
+++ b/arch/s390/kvm/guestdbg.c
@@ -206,7 +206,7 @@ static int __import_wp_info(struct kvm_vcpu *vcpu,
int kvm_s390_import_bp_data(struct kvm_vcpu *vcpu,
struct kvm_guest_debug *dbg)
{
- int ret = 0, nr_wp = 0, nr_bp = 0, i, size;
+ int ret = 0, nr_wp = 0, nr_bp = 0, i;
struct kvm_hw_breakpoint *bp_data = NULL;
struct kvm_hw_wp_info_arch *wp_info = NULL;
struct kvm_hw_bp_info_arch *bp_info = NULL;
@@ -216,14 +216,17 @@ int kvm_s390_import_bp_data(struct kvm_vcpu *vcpu,
else if (dbg->arch.nr_hw_bp > MAX_BP_COUNT)
return -EINVAL;

- size = dbg->arch.nr_hw_bp * sizeof(struct kvm_hw_breakpoint);
- bp_data = kmalloc(size, GFP_KERNEL);
+ bp_data = kmalloc_array(dbg->arch.nr_hw_bp,
+ sizeof(*bp_data),
+ GFP_KERNEL);
if (!bp_data) {
ret = -ENOMEM;
goto error;
}

- if (copy_from_user(bp_data, dbg->arch.hw_bp, size)) {
+ if (copy_from_user(bp_data,
+ dbg->arch.hw_bp,
+ sizeof(*bp_data) * dbg->arch.nr_hw_bp)) {
ret = -EFAULT;
goto error;
}
@@ -241,17 +244,19 @@ int kvm_s390_import_bp_data(struct kvm_vcpu *vcpu,
}
}

- size = nr_wp * sizeof(struct kvm_hw_wp_info_arch);
- if (size > 0) {
- wp_info = kmalloc(size, GFP_KERNEL);
+ if (nr_wp > 0) {
+ wp_info = kmalloc_array(nr_wp,
+ sizeof(*wp_info),
+ GFP_KERNEL);
if (!wp_info) {
ret = -ENOMEM;
goto error;
}
}
- size = nr_bp * sizeof(struct kvm_hw_bp_info_arch);
- if (size > 0) {
- bp_info = kmalloc(size, GFP_KERNEL);
+ if (nr_bp > 0) {
+ bp_info = kmalloc_array(nr_bp,
+ sizeof(*bp_info),
+ GFP_KERNEL);
if (!bp_info) {
ret = -ENOMEM;
goto error;
--
2.9.3