Commit 8616a2d0 authored by Jameson Miller's avatar Jameson Miller Committed by Junio C Hamano

block alloc: add validations around cache_entry lifecyle

Add an option (controlled by an environment variable) perform extra
validations on mem_pool allocated cache entries. When set:

  1) Invalidate cache_entry memory when discarding cache_entry.

  2) When discarding index_state struct, verify that all cache_entries
     were allocated from expected mem_pool.

  3) When discarding mem_pools, invalidate mem_pool memory.

This should provide extra checks that mem_pools and their allocated
cache_entries are being used as expected.
Signed-off-by: 's avatarJameson Miller <jamill@microsoft.com>
Signed-off-by: 's avatarJunio C Hamano <gitster@pobox.com>
parent 8e72d675
......@@ -380,6 +380,12 @@ struct cache_entry *make_empty_transient_cache_entry(size_t name_len);
*/
void discard_cache_entry(struct cache_entry *ce);
/*
* Check configuration if we should perform extra validation on cache
* entries.
*/
int should_validate_cache_entries(void);
/*
* Duplicate a cache_entry. Allocate memory for the new entry from a
* memory_pool. Takes into account cache_entry fields that are meant
......
......@@ -414,7 +414,10 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
trace_argv_printf(argv, "trace: built-in: git");
validate_cache_entries(&the_index);
status = p->fn(argc, argv, prefix);
validate_cache_entries(&the_index);
if (status)
return status;
......
......@@ -50,7 +50,7 @@ void mem_pool_init(struct mem_pool **mem_pool, size_t initial_size)
*mem_pool = pool;
}
void mem_pool_discard(struct mem_pool *mem_pool)
void mem_pool_discard(struct mem_pool *mem_pool, int invalidate_memory)
{
struct mp_block *block, *block_to_free;
......@@ -59,6 +59,10 @@ void mem_pool_discard(struct mem_pool *mem_pool)
{
block_to_free = block;
block = block->next_block;
if (invalidate_memory)
memset(block_to_free->space, 0xDD, ((char *)block_to_free->end) - ((char *)block_to_free->space));
free(block_to_free);
}
......
......@@ -29,7 +29,7 @@ void mem_pool_init(struct mem_pool **mem_pool, size_t initial_size);
/*
* Discard a memory pool and free all the memory it is responsible for.
*/
void mem_pool_discard(struct mem_pool *mem_pool);
void mem_pool_discard(struct mem_pool *mem_pool, int invalidate_memory);
/*
* Alloc memory from the mem_pool.
......
......@@ -2050,8 +2050,10 @@ int discard_index(struct index_state *istate)
* Cache entries in istate->cache[] should have been allocated
* from the memory pool associated with this index, or from an
* associated split_index. There is no need to free individual
* cache entries.
* cache entries. validate_cache_entries can detect when this
* assertion does not hold.
*/
validate_cache_entries(istate);
resolve_undo_clear_index(istate);
istate->cache_nr = 0;
......@@ -2068,13 +2070,45 @@ int discard_index(struct index_state *istate)
istate->untracked = NULL;
if (istate->ce_mem_pool) {
mem_pool_discard(istate->ce_mem_pool);
mem_pool_discard(istate->ce_mem_pool, should_validate_cache_entries());
istate->ce_mem_pool = NULL;
}
return 0;
}
/*
* Validate the cache entries of this index.
* All cache entries associated with this index
* should have been allocated by the memory pool
* associated with this index, or by a referenced
* split index.
*/
void validate_cache_entries(const struct index_state *istate)
{
int i;
if (!should_validate_cache_entries() ||!istate || !istate->initialized)
return;
for (i = 0; i < istate->cache_nr; i++) {
if (!istate) {
die("internal error: cache entry is not allocated from expected memory pool");
} else if (!istate->ce_mem_pool ||
!mem_pool_contains(istate->ce_mem_pool, istate->cache[i])) {
if (!istate->split_index ||
!istate->split_index->base ||
!istate->split_index->base->ce_mem_pool ||
!mem_pool_contains(istate->split_index->base->ce_mem_pool, istate->cache[i])) {
die("internal error: cache entry is not allocated from expected memory pool");
}
}
}
if (istate->split_index)
validate_cache_entries(istate->split_index->base);
}
int unmerged_index(const struct index_state *istate)
{
int i;
......@@ -2878,8 +2912,25 @@ struct cache_entry *dup_cache_entry(const struct cache_entry *ce,
void discard_cache_entry(struct cache_entry *ce)
{
if (ce && should_validate_cache_entries())
memset(ce, 0xCD, cache_entry_size(ce->ce_namelen));
if (ce && ce->mem_pool_allocated)
return;
free(ce);
}
int should_validate_cache_entries(void)
{
static int validate_index_cache_entries = -1;
if (validate_index_cache_entries < 0) {
if (getenv("GIT_TEST_VALIDATE_INDEX_CACHE_ENTRIES"))
validate_index_cache_entries = 1;
else
validate_index_cache_entries = 0;
}
return validate_index_cache_entries;
}
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