Fix up pointer issues with lib/libkvm

In particular,
- avoid dereferencing NULL pointers
- test pointers against NULL, not 0
- test for errout == NULL in the top-level functions (kvm_open, kvm_openfiles,
  kvm_open2, etc)
- Replace a realloc and free on failure with reallocf

Found with: devel/cocchinelle

Differential Revision: https://reviews.freebsd.org/D5954
MFC after: 1 week
Reviewed by: jhb
Sponsored by: EMC / Isilon Storage Division

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/libkvm/kvm_arm.c b/lib/libkvm/kvm_arm.c
index ae5fb5bc8646..eeda900063f2 100644
--- a/lib/libkvm/kvm_arm.c
+++ b/lib/libkvm/kvm_arm.c
@@ -117,7 +117,7 @@ _arm_initvtop(kvm_t *kd)
 	}
 
 	vm = _kvm_malloc(kd, sizeof(*vm));
-	if (vm == 0) {
+	if (vm == NULL) {
 		_kvm_err(kd, kd->program, "cannot allocate vm");
 		return (-1);
 	}
@@ -168,6 +168,10 @@ _arm_initvtop(kvm_t *kd)
 		return (-1);
 	}
 	l1pt = _kvm_malloc(kd, ARM_L1_TABLE_SIZE);
+	if (l1pt == NULL) {
+		_kvm_err(kd, kd->program, "cannot allocate l1pt");
+		return (-1);
+	}
 	if (kvm_read2(kd, pa, l1pt, ARM_L1_TABLE_SIZE) != ARM_L1_TABLE_SIZE) {
 		_kvm_err(kd, kd->program, "cannot read l1pt");
 		free(l1pt);