From 8d9401c2791ee2d2805b741b1ee3006041edcd3e Mon Sep 17 00:00:00 2001 From: Liam Merwick Date: Mon, 5 Nov 2018 21:38:38 +0000 Subject: block: Fix potential Null pointer dereferences in vvfat.c The calls to find_mapping_for_cluster() may return NULL but it isn't always checked for before dereferencing the value returned. Additionally, add some asserts to cover cases where NULL can't be returned but which might not be obvious at first glance. Signed-off-by: Liam Merwick Message-id: 1541453919-25973-5-git-send-email-Liam.Merwick@oracle.com [mreitz: Dropped superfluous check of "mapping" following an assertion that it is not NULL, and fixed some indentation] Signed-off-by: Max Reitz --- block/vvfat.c | 46 ++++++++++++++++++++++++++++++---------------- 1 file changed, 30 insertions(+), 16 deletions(-) (limited to 'block/vvfat.c') diff --git a/block/vvfat.c b/block/vvfat.c index e4df255d58..1de5de1db4 100644 --- a/block/vvfat.c +++ b/block/vvfat.c @@ -100,30 +100,26 @@ static inline void array_free(array_t* array) /* does not automatically grow */ static inline void* array_get(array_t* array,unsigned int index) { assert(index < array->next); + assert(array->pointer); return array->pointer + index * array->item_size; } -static inline int array_ensure_allocated(array_t* array, int index) +static inline void array_ensure_allocated(array_t *array, int index) { if((index + 1) * array->item_size > array->size) { int new_size = (index + 32) * array->item_size; array->pointer = g_realloc(array->pointer, new_size); - if (!array->pointer) - return -1; + assert(array->pointer); memset(array->pointer + array->size, 0, new_size - array->size); array->size = new_size; array->next = index + 1; } - - return 0; } static inline void* array_get_next(array_t* array) { unsigned int next = array->next; - if (array_ensure_allocated(array, next) < 0) - return NULL; - + array_ensure_allocated(array, next); array->next = next + 1; return array_get(array, next); } @@ -2422,16 +2418,13 @@ static int commit_direntries(BDRVVVFATState* s, direntry_t* direntry = array_get(&(s->directory), dir_index); uint32_t first_cluster = dir_index == 0 ? 0 : begin_of_direntry(direntry); mapping_t* mapping = find_mapping_for_cluster(s, first_cluster); - int factor = 0x10 * s->sectors_per_cluster; int old_cluster_count, new_cluster_count; - int current_dir_index = mapping->info.dir.first_dir_index; - int first_dir_index = current_dir_index; + int current_dir_index; + int first_dir_index; int ret, i; uint32_t c; -DLOG(fprintf(stderr, "commit_direntries for %s, parent_mapping_index %d\n", mapping->path, parent_mapping_index)); - assert(direntry); assert(mapping); assert(mapping->begin == first_cluster); @@ -2439,6 +2432,11 @@ DLOG(fprintf(stderr, "commit_direntries for %s, parent_mapping_index %d\n", mapp assert(mapping->mode & MODE_DIRECTORY); assert(dir_index == 0 || is_directory(direntry)); + DLOG(fprintf(stderr, "commit_direntries for %s, parent_mapping_index %d\n", + mapping->path, parent_mapping_index)); + + current_dir_index = mapping->info.dir.first_dir_index; + first_dir_index = current_dir_index; mapping->info.dir.parent_mapping_index = parent_mapping_index; if (first_cluster == 0) { @@ -2488,6 +2486,9 @@ DLOG(fprintf(stderr, "commit_direntries for %s, parent_mapping_index %d\n", mapp direntry = array_get(&(s->directory), first_dir_index + i); if (is_directory(direntry) && !is_dot(direntry)) { mapping = find_mapping_for_cluster(s, first_cluster); + if (mapping == NULL) { + return -1; + } assert(mapping->mode & MODE_DIRECTORY); ret = commit_direntries(s, first_dir_index + i, array_index(&(s->mapping), mapping)); @@ -2516,6 +2517,10 @@ static int commit_one_file(BDRVVVFATState* s, assert(offset < size); assert((offset % s->cluster_size) == 0); + if (mapping == NULL) { + return -1; + } + for (i = s->cluster_size; i < offset; i += s->cluster_size) c = modified_fat_get(s, c); @@ -2662,8 +2667,12 @@ static int handle_renames_and_mkdirs(BDRVVVFATState* s) if (commit->action == ACTION_RENAME) { mapping_t* mapping = find_mapping_for_cluster(s, commit->param.rename.cluster); - char* old_path = mapping->path; + char *old_path; + if (mapping == NULL) { + return -1; + } + old_path = mapping->path; assert(commit->path); mapping->path = commit->path; if (rename(old_path, mapping->path)) @@ -2684,10 +2693,15 @@ static int handle_renames_and_mkdirs(BDRVVVFATState* s) direntry_t* d = direntry + i; if (is_file(d) || (is_directory(d) && !is_dot(d))) { + int l; + char *new_path; mapping_t* m = find_mapping_for_cluster(s, begin_of_direntry(d)); - int l = strlen(m->path); - char* new_path = g_malloc(l + diff + 1); + if (m == NULL) { + return -1; + } + l = strlen(m->path); + new_path = g_malloc(l + diff + 1); assert(!strncmp(m->path, mapping->path, l2)); -- cgit v1.2.3