livepatch: Reorder to use before freeing a pointer

Clang static analysis reports this issue
livepatch-shadow-fix1.c:113:2: warning: Use of
  memory after it is freed
  pr_info("%s: dummy @ %p, prevented leak @ %p\n",
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The pointer is freed in the previous statement.
Reorder the pr_info to report before the free.

Similar issue in livepatch-shadow-fix2.c

Note that it is a false positive. pr_info() just prints the address.
The freed memory is not accessed. Well, the static analyzer could not
know this easily.

Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: David Vernet <void@manifault.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
[pmladek@suse.com: Note about that it was false positive.]
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220320015143.2208591-1-trix@redhat.com

diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c
index 918ce17..6701641 100644 (file)
--- a/samples/livepatch/livepatch-shadow-fix1.c
+++ b/samples/livepatch/livepatch-shadow-fix1.c
@@ -109,9 +109,9 @@ static void livepatch_fix1_dummy_leak_dtor(void *obj, void *shadow_data)
        void *d = obj;
        int **shadow_leak = shadow_data;
 
-       kfree(*shadow_leak);
        pr_info("%s: dummy @ %p, prevented leak @ %p\n",
                         __func__, d, *shadow_leak);
+       kfree(*shadow_leak);
 }
 
 static void livepatch_fix1_dummy_free(struct dummy *d)

diff --git a/samples/livepatch/livepatch-shadow-fix2.c b/samples/livepatch/livepatch-shadow-fix2.c
index 29fe5cd..361046a 100644 (file)
--- a/samples/livepatch/livepatch-shadow-fix2.c
+++ b/samples/livepatch/livepatch-shadow-fix2.c
@@ -61,9 +61,9 @@ static void livepatch_fix2_dummy_leak_dtor(void *obj, void *shadow_data)
        void *d = obj;
        int **shadow_leak = shadow_data;
 
-       kfree(*shadow_leak);
        pr_info("%s: dummy @ %p, prevented leak @ %p\n",
                         __func__, d, *shadow_leak);
+       kfree(*shadow_leak);
 }
 
 static void livepatch_fix2_dummy_free(struct dummy *d)