From 12c963421d045a127c413a0722062b9932c50aa9 Mon Sep 17 00:00:00 2001 From: Nick Clifton Date: Wed, 28 Feb 2018 11:50:49 +0000 Subject: [PATCH] Catch integer overflows/underflows when parsing corrupt DWARF FORM blocks. PR 22895 PR 22893 * dwarf2.c (read_n_bytes): Replace size parameter with dwarf_block pointer. Drop unused abfd parameter. Check the size of the block before initialising the data field. Return the end pointer if the size is invalid. (read_attribute_value): Adjust invocations of read_n_bytes. --- bfd/ChangeLog | 8 ++++++++ bfd/dwarf2.c | 36 +++++++++++++++++++++--------------- 2 files changed, 29 insertions(+), 15 deletions(-) diff --git a/bfd/ChangeLog b/bfd/ChangeLog index 42cc700..91bc2ef 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -5,6 +5,14 @@ 2018-02-28 Nick Clifton + PR 22895 + PR 22893 + * dwarf2.c (read_n_bytes): Replace size parameter with dwarf_block + pointer. Drop unused abfd parameter. Check the size of the block + before initialising the data field. Return the end pointer if the + size is invalid. + (read_attribute_value): Adjust invocations of read_n_bytes. + PR 22894 * dwarf1.c (parse_die): Check the length of form blocks before advancing the data pointer. diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c index 2413542..ca22db7 100644 --- a/bfd/dwarf2.c +++ b/bfd/dwarf2.c @@ -623,14 +623,24 @@ read_8_bytes (bfd *abfd, bfd_byte *buf, bfd_byte *end) } static bfd_byte * -read_n_bytes (bfd *abfd ATTRIBUTE_UNUSED, - bfd_byte *buf, - bfd_byte *end, - unsigned int size ATTRIBUTE_UNUSED) +read_n_bytes (bfd_byte * buf, + bfd_byte * end, + struct dwarf_block * block) { - if (buf + size > end) - return NULL; - return buf; + unsigned int size = block->size; + bfd_byte * block_end = buf + size; + + if (block_end > end || block_end < buf) + { + block->data = NULL; + block->size = 0; + return end; + } + else + { + block->data = buf; + return block_end; + } } /* Scans a NUL terminated string starting at BUF, returning a pointer to it. @@ -1128,8 +1138,7 @@ read_attribute_value (struct attribute * attr, return NULL; blk->size = read_2_bytes (abfd, info_ptr, info_ptr_end); info_ptr += 2; - blk->data = read_n_bytes (abfd, info_ptr, info_ptr_end, blk->size); - info_ptr += blk->size; + info_ptr = read_n_bytes (info_ptr, info_ptr_end, blk); attr->u.blk = blk; break; case DW_FORM_block4: @@ -1139,8 +1148,7 @@ read_attribute_value (struct attribute * attr, return NULL; blk->size = read_4_bytes (abfd, info_ptr, info_ptr_end); info_ptr += 4; - blk->data = read_n_bytes (abfd, info_ptr, info_ptr_end, blk->size); - info_ptr += blk->size; + info_ptr = read_n_bytes (info_ptr, info_ptr_end, blk); attr->u.blk = blk; break; case DW_FORM_data2: @@ -1180,8 +1188,7 @@ read_attribute_value (struct attribute * attr, blk->size = _bfd_safe_read_leb128 (abfd, info_ptr, &bytes_read, FALSE, info_ptr_end); info_ptr += bytes_read; - blk->data = read_n_bytes (abfd, info_ptr, info_ptr_end, blk->size); - info_ptr += blk->size; + info_ptr = read_n_bytes (info_ptr, info_ptr_end, blk); attr->u.blk = blk; break; case DW_FORM_block1: @@ -1191,8 +1198,7 @@ read_attribute_value (struct attribute * attr, return NULL; blk->size = read_1_byte (abfd, info_ptr, info_ptr_end); info_ptr += 1; - blk->data = read_n_bytes (abfd, info_ptr, info_ptr_end, blk->size); - info_ptr += blk->size; + info_ptr = read_n_bytes (info_ptr, info_ptr_end, blk); attr->u.blk = blk; break; case DW_FORM_data1: -- 2.7.4