• Petr Mladek's avatar
    livepatch/samples/selftest: Use klp_shadow_alloc() API correctly · be6da984
    Petr Mladek authored
    The commit e91c2518 ("livepatch: Initialize shadow variables
    safely by a custom callback") leads to the following static checker
    warning:
    
      samples/livepatch/livepatch-shadow-fix1.c:86 livepatch_fix1_dummy_alloc()
      error: 'klp_shadow_alloc()' 'leak' too small (4 vs 8)
    
    It is because klp_shadow_alloc() is used a wrong way:
    
      int *leak;
      shadow_leak = klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL,
    				 shadow_leak_ctor, leak);
    
    The code is supposed to store the "leak" pointer into the shadow variable.
    3rd parameter correctly passes size of the data (size of pointer). But
    the 5th parameter is wrong. It should pass pointer to the data (pointer
    to the pointer) but it passes the pointer directly.
    
    It works because shadow_leak_ctor() handle "ctor_data" as the data
    instead of pointer to the data. But it is semantically wrong and
    confusing.
    
    The same problem is also in the module used by selftests. In this case,
    "pvX" variables are introduced. They represent the data stored in
    the shadow variables.
    Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
    Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
    Reviewed-by: default avatarJoe Lawrence <joe.lawrence@redhat.com>
    Acked-by: default avatarMiroslav Benes <mbenes@suse.cz>
    Reviewed-by: default avatarKamalesh Babulal <kamalesh@linux.vnet.ibm.com>
    Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
    be6da984
test_klp_shadow_vars.c 6.42 KB