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Fix race in git_packfile_unpack.

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Increment refcount of newly added cache entries just like existing
entries looked up from the cache. Otherwise the new entry can be
evicted from the cache and destroyed while it's still in use.
This commit is contained in:
Jason Haslam 2015-02-14 23:43:26 -07:00
parent 57f45e7f4d
commit 8588cb0cbf
1 changed files with 9 additions and 2 deletions
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11
src/pack.c
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@ -56,6 +56,7 @@ static git_pack_cache_entry *new_cache_object(git_rawobj *source)
if (!e)
return NULL;
git_atomic_inc(&e->refcount);
memcpy(&e->raw, source, sizeof(git_rawobj));
return e;
@ -145,7 +146,11 @@ static void free_lowest_entry(git_pack_cache *cache)
}
}
static int cache_add(git_pack_cache *cache, git_rawobj *base, git_off_t offset)
static int cache_add(
git_pack_cache_entry **cached_out,
git_pack_cache *cache,
git_rawobj *base,
git_off_t offset)
{
git_pack_cache_entry *entry;
int error, exists = 0;
@ -171,6 +176,8 @@ static int cache_add(git_pack_cache *cache, git_rawobj *base, git_off_t offset)
assert(error != 0);
kh_value(cache->entries, k) = entry;
cache->memory_used += entry->raw.len;
*cached_out = entry;
}
git_mutex_unlock(&cache->lock);
/* Somebody beat us to adding it into the cache */
@ -699,7 +706,7 @@ int git_packfile_unpack(
* long as it's not already the cached one.
*/
if (!cached)
free_base = !!cache_add(&p->bases, obj, elem->base_key);
free_base = !!cache_add(&cached, &p->bases, obj, elem->base_key);
elem = &stack[elem_pos - 1];
curpos = elem->offset;