coverity: Improve model for GLib memory allocation
In current versions of GLib, g_new() may expand into g_malloc_n(). When it does, Coverity can't see the memory allocation, because we don't model g_malloc_n(). Similarly for g_new0(), g_renew(), g_try_new(), g_try_new0(), g_try_renew(). Model g_malloc_n(), g_malloc0_n(), g_realloc_n(). Model g_try_malloc_n(), g_try_malloc0_n(), g_try_realloc_n() by adding indeterminate out of memory conditions on top. To avoid undue duplication, replace the existing models for g_malloc() & friends by trivial wrappers around g_malloc_n() & friends. In a local scan, this flags four additional RESOURCE_LEAKs and one NULL_RETURNS. The NULL_RETURNS is a false positive: Coverity can now see that g_try_malloc(l1_sz * sizeof(uint64_t)) in qcow2_check_metadata_overlap() may return NULL, but is too stupid to recognize that a loop executing l1_sz times won't be entered then. Three out of the four RESOURCE_LEAKs appear genuine. The false positive is in ppce500_prep_device_tree(): the pointer dies, but a pointer to a struct member escapes, and we get the pointer back for freeing with container_of(). Too funky for Coverity. Signed-off-by: Markus Armbruster <armbru@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -90,7 +90,8 @@ static int get_keysym(const name2keysym_t *table,
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}
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}
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/* glib memory allocation functions.
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/*
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* GLib memory allocation functions.
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*
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* Note that we ignore the fact that g_malloc of 0 bytes returns NULL,
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* and g_realloc of 0 bytes frees the pointer.
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@ -107,60 +108,128 @@ static int get_keysym(const name2keysym_t *table,
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* we'll get a buffer overflow reported anyway.
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*/
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void *malloc(size_t);
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void *calloc(size_t, size_t);
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void *realloc(void *, size_t);
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void free(void *);
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/*
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* Allocation primitives, cannot return NULL
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* See also Coverity's library/generic/libc/all/all.c
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*/
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void *
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g_malloc(size_t n_bytes)
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void *g_malloc_n(size_t nmemb, size_t size)
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{
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void *mem;
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__coverity_negative_sink__(n_bytes);
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mem = malloc(n_bytes == 0 ? 1 : n_bytes);
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if (!mem) __coverity_panic__();
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return mem;
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size_t sz;
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void *ptr;
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__coverity_negative_sink__(nmemb);
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__coverity_negative_sink__(size);
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sz = nmemb * size;
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ptr = __coverity_alloc__(size);
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__coverity_mark_as_uninitialized_buffer__(ptr);
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__coverity_mark_as_afm_allocated__(ptr, AFM_free);
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return ptr;
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}
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void *
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g_malloc0(size_t n_bytes)
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void *g_malloc0_n(size_t nmemb, size_t size)
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{
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void *mem;
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__coverity_negative_sink__(n_bytes);
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mem = calloc(1, n_bytes == 0 ? 1 : n_bytes);
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if (!mem) __coverity_panic__();
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return mem;
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size_t sz;
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void *ptr;
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__coverity_negative_sink__(nmemb);
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__coverity_negative_sink__(size);
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sz = nmemb * size;
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ptr = __coverity_alloc__(size);
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__coverity_writeall0__(ptr);
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__coverity_mark_as_afm_allocated__(ptr, AFM_free);
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return ptr;
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}
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void g_free(void *mem)
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void *g_realloc_n(void *ptr, size_t nmemb, size_t size)
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{
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free(mem);
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size_t sz;
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__coverity_negative_sink__(nmemb);
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__coverity_negative_sink__(size);
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sz = nmemb * size;
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__coverity_escape__(ptr);
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ptr = __coverity_alloc__(size);
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/*
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* Memory beyond the old size isn't actually initialized. Can't
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* model that. See Coverity's realloc() model
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*/
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__coverity_writeall__(ptr);
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__coverity_mark_as_afm_allocated__(ptr, AFM_free);
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return ptr;
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}
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void *g_realloc(void * mem, size_t n_bytes)
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void g_free(void *ptr)
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{
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__coverity_negative_sink__(n_bytes);
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mem = realloc(mem, n_bytes == 0 ? 1 : n_bytes);
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if (!mem) __coverity_panic__();
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return mem;
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__coverity_free__(ptr);
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__coverity_mark_as_afm_freed__(ptr, AFM_free);
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}
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void *g_try_malloc(size_t n_bytes)
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/*
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* Derive the g_try_FOO_n() from the g_FOO_n() by adding indeterminate
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* out of memory conditions
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*/
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void *g_try_malloc_n(size_t nmemb, size_t size)
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{
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__coverity_negative_sink__(n_bytes);
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return malloc(n_bytes == 0 ? 1 : n_bytes);
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int nomem;
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if (nomem) {
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return NULL;
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}
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return g_malloc_n(nmemb, size);
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}
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void *g_try_malloc0(size_t n_bytes)
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void *g_try_malloc0_n(size_t nmemb, size_t size)
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{
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__coverity_negative_sink__(n_bytes);
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return calloc(1, n_bytes == 0 ? 1 : n_bytes);
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int nomem;
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if (nomem) {
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return NULL;
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}
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return g_malloc0_n(nmemb, size);
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}
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void *g_try_realloc(void *mem, size_t n_bytes)
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void *g_try_realloc_n(void *ptr, size_t nmemb, size_t size)
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{
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__coverity_negative_sink__(n_bytes);
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return realloc(mem, n_bytes == 0 ? 1 : n_bytes);
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int nomem;
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if (nomem) {
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return NULL;
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}
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return g_realloc_n(ptr, nmemb, size);
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}
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/* Trivially derive the g_FOO() from the g_FOO_n() */
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void *g_malloc(size_t size)
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{
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return g_malloc_n(1, size);
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}
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void *g_malloc0(size_t size)
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{
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return g_malloc0_n(1, size);
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}
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void *g_realloc(void *ptr, size_t size)
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{
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return g_realloc_n(ptr, 1, size);
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}
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void *g_try_malloc(size_t size)
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{
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return g_try_malloc_n(1, size);
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}
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void *g_try_malloc0(size_t size)
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{
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return g_try_malloc0_n(1, size);
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}
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void *g_try_realloc(void *ptr, size_t size)
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{
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return g_try_realloc_n(ptr, 1, size);
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}
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/* Other glib functions */
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