Messages in this thread | | | Date | Mon, 19 Nov 2018 12:02:33 -0600 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v3 2/2] objtool: fix .cold functions parent symbols search |
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On Mon, Nov 12, 2018 at 01:55:19PM +0100, Artem Savkov wrote: > Because find_symbol_by_name() traverses the same lists as read_symbols() > changing sym->name in place without copying it affects the result of > find_symbol_by_name() and, in case when ".cold" function precedes it's > parent in sec->symbol_list, can result in function being considered a > parent of itself. This leads to function length being set to 0 and other > consequent side-effects including a segfault in add_switch_table(). > The effects of this bug are only visible when building with > -ffunction-sections in KCFLAGS. > > Fix by copying the search string instead of modifying it in place. > > Fixes: 13810435b9a7 "objtool: Support GCC 8's cold subfunctions"
Same here, needs parentheses.
> Signed-off-by: Artem Savkov <asavkov@redhat.com> > --- > tools/objtool/elf.c | 17 ++++++++++++++--- > 1 file changed, 14 insertions(+), 3 deletions(-) > > diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c > index 3decd43477df..15d9acfb2c97 100644 > --- a/tools/objtool/elf.c > +++ b/tools/objtool/elf.c > @@ -31,6 +31,8 @@ > #include "elf.h" > #include "warn.h" > > +#define MAX_NAME_LEN 128 > + > struct section *find_section_by_name(struct elf *elf, const char *name) > { > struct section *sec; > @@ -298,6 +300,8 @@ 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[MAX_NAME_LEN + 1]; > + size_t pnamelen; > if (sym->type != STT_FUNC) > continue; > sym->pfunc = sym->cfunc = sym; > @@ -305,9 +309,16 @@ static int read_symbols(struct elf *elf) > if (!coldstr) > continue; > > - coldstr[0] = '\0'; > - pfunc = find_symbol_by_name(elf, sym->name); > - coldstr[0] = '.'; > + pnamelen = coldstr - sym->name; > + if (pnamelen > MAX_NAME_LEN) { > + WARN("%s(): parent function name exceeds maximum length of %d characters", > + sym->name, MAX_NAME_LEN); > + goto cold_err;
Same here, makes more sense to just return -1 and let elf_close() clean it up I think.
-- Josh
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