livepatch: check kzalloc return values

kzalloc() return should always be checked - notably in example code
where this may be seen as reference. On failure of allocation in
livepatch_fix1_dummy_alloc() respectively dummy_alloc() previous
allocation is freed (thanks to Petr Mladek <pmladek@suse.com> for
catching this) and NULL returned.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Fixes: 439e7271dc2b ("livepatch: introduce shadow variable API")
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

2 files changed, 9 insertions, 0 deletions

diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c
index 49b13553eaae..e8f1bd6b29b1 100644
--- a/samples/livepatch/livepatch-shadow-fix1.c
+++ b/samples/livepatch/livepatch-shadow-fix1.c
@@ -89,6 +89,11 @@ struct dummy *livepatch_fix1_dummy_alloc(void)
          * pointer to handle resource release.
          */
         leak = kzalloc(sizeof(int), GFP_KERNEL);
+        if (!leak) {
+                kfree(d);
+                return NULL;
+        }
+
         klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL,
                          shadow_leak_ctor, leak);
 
diff --git a/samples/livepatch/livepatch-shadow-mod.c b/samples/livepatch/livepatch-shadow-mod.c
index 4c54b250332d..4aa8a88d3cd6 100644
--- a/samples/livepatch/livepatch-shadow-mod.c
+++ b/samples/livepatch/livepatch-shadow-mod.c
@@ -118,6 +118,10 @@ noinline struct dummy *dummy_alloc(void)
 
         /* Oops, forgot to save leak! */
         leak = kzalloc(sizeof(int), GFP_KERNEL);
+        if (!leak) {
+                kfree(d);
+                return NULL;
+        }
 
         pr_info("%s: dummy @ %p, expires @ %lx\n",
                 __func__, d, d->jiffies_expire);