When calulating the possible section header table end us the actual size of the section headers (sizeof (Elf32_Shdr) or sizeof (Elf64_Shdr)), not the ELF header e_shentsize value, which can be corrupted. This prevents a posssible overflow, but we check the shdrs_end is sane later anyway.
https://sourceware.org/bugzilla/show_bug.cgi?id=28659 Signed-off-by: Mark Wielaard <m...@klomp.org> --- libdwfl/ChangeLog | 5 +++++ libdwfl/dwfl_segment_report_module.c | 4 ++-- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog index 8dd595f8..5e25c1b0 100644 --- a/libdwfl/ChangeLog +++ b/libdwfl/ChangeLog @@ -1,3 +1,8 @@ +2021-12-08 Mark Wielaard <m...@klomp.org> + + * dwfl_segment_report_module.c (dwfl_segment_report_module): Don't + trust e_shentsize. + 2021-12-08 Mark Wielaard <m...@klomp.org> * link_map.c (dwfl_link_map_report): Make sure phent != 0. diff --git a/libdwfl/dwfl_segment_report_module.c b/libdwfl/dwfl_segment_report_module.c index ee9cfa2e..5efc9d6a 100644 --- a/libdwfl/dwfl_segment_report_module.c +++ b/libdwfl/dwfl_segment_report_module.c @@ -383,7 +383,7 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name, zero sh_size field. We ignore this here because getting shdrs is just a nice bonus (see below in the type == PT_LOAD case where we trim the last segment). */ - shdrs_end = ehdr.e32.e_shoff + ehdr.e32.e_shnum * ehdr.e32.e_shentsize; + shdrs_end = ehdr.e32.e_shoff + ehdr.e32.e_shnum * sizeof (Elf32_Shdr); break; case ELFCLASS64: @@ -397,7 +397,7 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name, if (phentsize != sizeof (Elf64_Phdr)) goto out; /* See the NOTE above for shdrs_end and ehdr.e32.e_shnum. */ - shdrs_end = ehdr.e64.e_shoff + ehdr.e64.e_shnum * ehdr.e64.e_shentsize; + shdrs_end = ehdr.e64.e_shoff + ehdr.e64.e_shnum * sizeof (Elf64_Shdr); break; default: -- 2.30.2
