From a4ca24c4fe316bc102b9fa52f808d206ab8cd24b Mon Sep 17 00:00:00 2001 From: Filippo Bigarella Date: Thu, 10 Nov 2016 01:31:23 +0100 Subject: bplist: Prevent out-of-bounds read in plist_from_bin() when parsing offset_table offset_table_index is read from the file, so we have full control over it. This means we can point offset_table essentially anywhere we want, which can lead to an out-of-bounds read when it will be used later on. --- src/bplist.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'src/bplist.c') diff --git a/src/bplist.c b/src/bplist.c index 8447187..be82b4e 100644 --- a/src/bplist.c +++ b/src/bplist.c @@ -708,6 +708,7 @@ PLIST_API void plist_from_bin(const char *plist_bin, uint32_t length, plist_t * uint64_t num_objects = 0; uint64_t root_object = 0; uint64_t offset_table_index = 0; + char *offset_table = NULL; //first check we have enough data if (!(length >= BPLIST_MAGIC_SIZE + BPLIST_VERSION_SIZE + BPLIST_TRL_SIZE)) @@ -727,6 +728,7 @@ PLIST_API void plist_from_bin(const char *plist_bin, uint32_t length, plist_t * num_objects = be64dec(trailer + BPLIST_TRL_NUMOBJ_IDX); root_object = be64dec(trailer + BPLIST_TRL_ROOTOBJ_IDX); offset_table_index = be64dec(trailer + BPLIST_TRL_OFFTAB_IDX); + offset_table = (char *) (plist_bin + offset_table_index); if (num_objects == 0) return; @@ -734,13 +736,19 @@ PLIST_API void plist_from_bin(const char *plist_bin, uint32_t length, plist_t * if (root_object >= num_objects) return; + if (offset_table < plist_bin || offset_table >= plist_bin + length) + return; + + if (offset_table + num_objects * offset_size >= plist_bin + length) + return; + struct bplist_data bplist; bplist.data = plist_bin; bplist.size = length; bplist.num_objects = num_objects; bplist.dict_size = dict_size; bplist.offset_size = offset_size; - bplist.offset_table = (char *) (plist_bin + offset_table_index); + bplist.offset_table = offset_table; bplist.level = 0; bplist.used_indexes = (uint32_t*)malloc(sizeof(uint32_t) * num_objects); -- cgit v1.1-32-gdbae