[PATCH v2 12/45] test: Support testing malloc() failures

[Simon Glass]

Hi Sean,

On Wed, 28 Sept 2022 at 11:18, Sean Anderson <seanga2 at gmail.com> wrote:
>
> On 9/6/22 22:27, Simon Glass wrote:
> > It is helpful to test that out-of-memory checks work correctly in code
> > that calls malloc().
> >
> > Add a simple way to force failure after a given number of malloc() calls.
> >
> > Fix a header guard to avoid a build error on sandbox_vpl.
> >
> > Signed-off-by: Simon Glass <sjg at chromium.org>
> > ---
> >
> > (no changes since v1)
> >
> >   arch/sandbox/include/asm/malloc.h |  1 +
> >   common/dlmalloc.c                 | 19 +++++++++++++++++++
> >   include/malloc.h                  | 12 ++++++++++++
> >   test/test-main.c                  |  1 +
> >   4 files changed, 33 insertions(+)
> >
> > diff --git a/arch/sandbox/include/asm/malloc.h b/arch/sandbox/include/asm/malloc.h
> > index a1467b5eadd..8aaaa9cb87b 100644
> > --- a/arch/sandbox/include/asm/malloc.h
> > +++ b/arch/sandbox/include/asm/malloc.h
> > @@ -6,6 +6,7 @@
> >    */
> >
> >   #ifndef __ASM_MALLOC_H
> > +#define __ASM_MALLOC_H
> >
> >   void *malloc(size_t size);
> >   void free(void *ptr);
> > diff --git a/common/dlmalloc.c b/common/dlmalloc.c
> > index f48cd2a333d..41c7230424c 100644
> > --- a/common/dlmalloc.c
> > +++ b/common/dlmalloc.c
> > @@ -596,6 +596,9 @@ ulong mem_malloc_start = 0;
> >   ulong mem_malloc_end = 0;
> >   ulong mem_malloc_brk = 0;
> >
> > +static bool malloc_testing;  /* enable test mode */
> > +static int malloc_max_allocs;        /* return NULL after this many calls to malloc() */
> > +
> >   void *sbrk(ptrdiff_t increment)
> >   {
> >       ulong old = mem_malloc_brk;
> > @@ -1307,6 +1310,11 @@ Void_t* mALLOc(bytes) size_t bytes;
> >               return malloc_simple(bytes);
> >   #endif
> >
> > +  if (CONFIG_IS_ENABLED(UNIT_TEST) && malloc_testing) {
> > +    if (--malloc_max_allocs < 0)
> > +      return NULL;
> > +  }
> > +
> >     /* check if mem_malloc_init() was run */
> >     if ((mem_malloc_start == 0) && (mem_malloc_end == 0)) {
> >       /* not initialized yet */
> > @@ -2470,6 +2478,17 @@ int initf_malloc(void)
> >       return 0;
> >   }
> >
> > +void malloc_enable_testing(int max_allocs)
> > +{
> > +     malloc_testing = true;
> > +     malloc_max_allocs = max_allocs;
> > +}
> > +
> > +void malloc_disable_testing(void)
> > +{
> > +     malloc_testing = false;
> > +}
> > +
> >   /*
> >
> >   History:
> > diff --git a/include/malloc.h b/include/malloc.h
> > index e8c8b254c0d..161ccbd1298 100644
> > --- a/include/malloc.h
> > +++ b/include/malloc.h
> > @@ -883,6 +883,18 @@ extern Void_t*     sbrk();
> >
> >   void malloc_simple_info(void);
> >
> > +/**
> > + * malloc_enable_testing() - Put malloc() into test mode
> > + *
> > + * This only works if UNIT_TESTING is enabled
> > + *
> > + * @max_allocs: return -ENOMEM after max_allocs calls to malloc()
> > + */
> > +void malloc_enable_testing(int max_allocs);
> > +
> > +/** malloc_disable_testing() - Put malloc() into normal mode */
> > +void malloc_disable_testing(void);
> > +
> >   #if CONFIG_IS_ENABLED(SYS_MALLOC_SIMPLE)
> >   #define malloc malloc_simple
> >   #define realloc realloc_simple
> > diff --git a/test/test-main.c b/test/test-main.c
> > index c65cbd7c351..5b6b5ba5bbe 100644
> > --- a/test/test-main.c
> > +++ b/test/test-main.c
> > @@ -46,6 +46,7 @@ static int dm_test_pre_run(struct unit_test_state *uts)
> >       uts->force_fail_alloc = false;
> >       uts->skip_post_probe = false;
> >       gd->dm_root = NULL;
> > +     malloc_disable_testing();
> >       if (CONFIG_IS_ENABLED(UT_DM) && !CONFIG_IS_ENABLED(OF_PLATDATA))
> >               memset(dm_testdrv_op_count, '\0', sizeof(dm_testdrv_op_count));
> >       arch_reset_for_test();
>
> Reviewed-by: Sean Anderson <seanga2 at gmail.com>
>
> but do we need to instrument rEALLOc too?

We could, but I'd prefer to have a test which needs it first. Actually
realloc() calls malloc() in some cases, so we are already messing with
things here.

Regards,
Simon