From 54392c4df604f2015cafce6f362686c0ef7d2ce7 Mon Sep 17 00:00:00 2001 From: Andrew Burgess Date: Thu, 14 Sep 2023 13:06:26 +0100 Subject: [PATCH] gdb: fix buffer overflow in DWARF reader In this commit: commit 48ac197b0c209ccf1f2de9704eb6cdf7c5c73a8e Date: Fri Nov 19 10:12:44 2021 -0700 Handle multiple addresses in call_site_target a buffer overflow bug was introduced when the following code was added: CORE_ADDR *saved = XOBNEWVAR (&objfile->objfile_obstack, CORE_ADDR, addresses.size ()); std::copy (addresses.begin (), addresses.end (), saved); The definition of XOBNEWVAR is (from libiberty.h): #define XOBNEWVAR(O, T, S) ((T *) obstack_alloc ((O), (S))) So 'saved' is going to point to addresses.size () bytes of memory, however, the std::copy will write addresses.size () number of CORE_ADDR sized entries to the address pointed to by 'saved', this is going to result in memory corruption. The mistake is that we should have used XOBNEWVEC, which allocates a vector of entries, the definition of XOBNEWVEC is: #define XOBNEWVEC(O, T, N) \ ((T *) obstack_alloc ((O), sizeof (T) * (N))) Which means we will have set aside enough space to create a copy of the contents of the addresses vector. I'm not sure how to create a test for this problem, this issue cropped up when debugging a particular i686 built binary, which just happened to trigger a glibc assertion (likely due to random memory corruption), debugging the same binary built for x86-64 appeared to work just fine. Using valgrind on the failing GDB binary pointed straight to the cause of the problem, and with this patch in place there are no longer valgrind errors in this area. If anyone has ideas for a test I'm happy to work on something. Co-Authored-By: Keith Seitz Approved-By: Tom Tromey --- gdb/dwarf2/read.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index 98bedbc5d49..0f4d99109fb 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -10548,7 +10548,7 @@ read_call_site_scope (struct die_info *die, struct dwarf2_cu *cu) std::vector addresses; dwarf2_ranges_read_low_addrs (ranges_offset, target_cu, target_die->tag, addresses); - unrelocated_addr *saved = XOBNEWVAR (&objfile->objfile_obstack, + unrelocated_addr *saved = XOBNEWVEC (&objfile->objfile_obstack, unrelocated_addr, addresses.size ()); std::copy (addresses.begin (), addresses.end (), saved); -- 2.30.2