Hi Mark, On Sun, Jun 22, 2025 at 10:19 AM Mark Wielaard <m...@klomp.org> wrote: > > dwfl_module_getsym returns the name of a symbol as found in the > corresponding (symbol) string section. Make sure all names are > correctly zero terminated by making sure the last valid index in a > section/segment Elf_Data contains a zero character. > > * libdwfl/dwfl_module_getdwarf.c (validate_strdata): New > function taking Elf_Data and restricting d_size to last zero > char. > (translate_offs): Call validate_strdata. > (find_symtab): Likewise for both symstrdata and aux_symstrdata. > > https://sourceware.org/bugzilla/show_bug.cgi?id=33099 > > Signed-off-by: Mark Wielaard <m...@klomp.org> > --- > libdwfl/dwfl_module_getdwarf.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/libdwfl/dwfl_module_getdwarf.c b/libdwfl/dwfl_module_getdwarf.c > index 7fd0d3aa3b17..135132d69178 100644 > --- a/libdwfl/dwfl_module_getdwarf.c > +++ b/libdwfl/dwfl_module_getdwarf.c > @@ -1,5 +1,6 @@ > /* Find debugging and symbol information for a module in libdwfl. > Copyright (C) 2005-2012, 2014, 2015, 2025 Red Hat, Inc. > + Copyright (C) 2025 Mark J. Wielaard <m...@klomp.org> > This file is part of elfutils. > > This file is free software; you can redistribute it and/or modify > @@ -692,6 +693,19 @@ find_offsets (Elf *elf, GElf_Addr main_bias, size_t > phnum, size_t n, > } > } > > +/* This is a string section/segment, so we want to make sure the last > + valid index contains a zero character to terminate a string. */ > +static void > +validate_strdata (Elf_Data *symstrdata) > +{ > + size_t size = symstrdata->d_size; > + const char *buf = symstrdata->d_buf; > + while (size > 0 && *(buf + size - 1) != '\0') > + --size; > + symstrdata->d_size = size; > +} > + > + > /* Various addresses we might want to pull from the dynamic segment. */ > enum > { > @@ -816,6 +830,8 @@ translate_offs (GElf_Addr adjust, > ELF_T_BYTE); > if (mod->symstrdata == NULL) > mod->symdata = NULL; > + else > + validate_strdata (mod->symstrdata); > } > if (mod->symdata == NULL) > mod->symerr = DWFL_E (LIBELF, elf_errno ()); > @@ -1181,6 +1197,8 @@ find_symtab (Dwfl_Module *mod) > mod->symstrdata = elf_getdata (symstrscn, NULL); > if (mod->symstrdata == NULL || mod->symstrdata->d_buf == NULL) > goto elferr; > + else > + validate_strdata (mod->symstrdata); > > if (xndxscn == NULL) > mod->symxndxdata = NULL; > @@ -1264,6 +1282,8 @@ find_symtab (Dwfl_Module *mod) > mod->aux_symstrdata = elf_getdata (aux_strscn, NULL); > if (mod->aux_symstrdata == NULL || mod->aux_symstrdata->d_buf == NULL) > goto aux_cleanup; > + else > + validate_strdata (mod->aux_symstrdata); > > if (aux_xndxscn == NULL) > mod->aux_symxndxdata = NULL; > -- > 2.49.0 >
LGTM. Aaron
