If we are going to dereference a pointer there should be at least enough data to hold a pointer. Found by afl-fuzz.
Signed-off-by: Mark Wielaard <[email protected]> --- libdw/ChangeLog | 5 +++++ libdw/encoded-value.h | 7 ++++--- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/libdw/ChangeLog b/libdw/ChangeLog index 2757093..aa4d09c 100644 --- a/libdw/ChangeLog +++ b/libdw/ChangeLog @@ -1,3 +1,8 @@ +2015-05-27 Mark Wielaard <[email protected]> + + * encoded-value.h (read_encoded_value): Check data d_size contains + at least enough data to hold a pointer for DW_EH_PE_indirect. + 2015-05-22 Mark Wielaard <[email protected]> * dwarf_getsrclines.c (read_srclines): Limit stack usage of lines diff --git a/libdw/encoded-value.h b/libdw/encoded-value.h index 0fa2018..48d868f 100644 --- a/libdw/encoded-value.h +++ b/libdw/encoded-value.h @@ -214,9 +214,10 @@ read_encoded_value (const Dwarf_CFI *cache, uint8_t encoding, if (unlikely (*result < cache->frame_vaddr)) return true; *result -= cache->frame_vaddr; - if (unlikely (*result > (cache->data->d.d_size - - encoded_value_size (NULL, cache->e_ident, - DW_EH_PE_absptr, NULL)))) + size_t ptrsize = encoded_value_size (NULL, cache->e_ident, + DW_EH_PE_absptr, NULL); + if (unlikely (cache->data->d.d_size < ptrsize + || *result > (cache->data->d.d_size - ptrsize))) return true; const uint8_t *ptr = cache->data->d.d_buf + *result; if (unlikely (__libdw_cfi_read_address_inc (cache, &ptr, 0, result) -- 1.8.3.1
