Messages in this thread | | | Date | Wed, 7 Nov 2018 11:08:56 -0600 | From | Josh Poimboeuf <> | Subject | Re: [PATCH] objtool: fix .cold. functions parent symbols search |
| |
On Wed, Nov 07, 2018 at 03:05:59PM +0100, Artem Savkov wrote: > The way it is currently done it is possible for read_symbols() to find the > same symbol as parent for ".cold" functions.
I seem to remember having this discussion for kpatch-build, but I forget the details. Can you explain how this can happen (and also add that detail to the commit message)? I haven't seen any bug reports, is it purely theoretical?
> This leads to a bunch of > complications such as func length being set to 0 and a segfault in > add_switch_table(). Fix by copying the search string instead of modifying > it in place. > > Signed-off-by: Artem Savkov <asavkov@redhat.com> > --- > tools/objtool/elf.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c > index 6dbb9fae0f9d..781c8afb29b9 100644 > --- a/tools/objtool/elf.c > +++ b/tools/objtool/elf.c > @@ -298,6 +298,7 @@ static int read_symbols(struct elf *elf) > /* Create parent/child links for any cold subfunctions */ > list_for_each_entry(sec, &elf->sections, list) { > list_for_each_entry(sym, &sec->symbol_list, list) { > + char *pname; > if (sym->type != STT_FUNC) > continue; > sym->pfunc = sym->cfunc = sym; > @@ -305,9 +306,9 @@ static int read_symbols(struct elf *elf) > if (!coldstr) > continue; > > - coldstr[0] = '\0'; > - pfunc = find_symbol_by_name(elf, sym->name); > - coldstr[0] = '.'; > + pname = strndup(sym->name, coldstr - sym->name); > + pfunc = find_symbol_by_name(elf, pname); > + free(pname); > > if (!pfunc) { > WARN("%s(): can't find parent function", > -- > 2.17.2 >
-- Josh
| |