* [PATCH v1] perf symbol: Avoid use after free
@ 2023-03-28 23:44 Ian Rogers
2023-03-29 4:52 ` Adrian Hunter
0 siblings, 1 reply; 4+ messages in thread
From: Ian Rogers @ 2023-03-28 23:44 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Namhyung Kim,
Ian Rogers, Adrian Hunter, Leo Yan, linux-perf-users,
linux-kernel
If demangling succeeds then sym_name is set to the demangled string
that is freed. Rather than test if sym_name is empty and possibly
use-after-free on the return path, expand out the alternatives.
Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/symbol-elf.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index c0a2de42c51b..b7e3e492bff3 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -577,15 +577,17 @@ static bool get_plt_got_name(GElf_Shdr *shdr, size_t i,
/* Get the associated symbol */
gelf_getsym(di->dynsym_data, vr->sym_idx, &sym);
sym_name = elf_sym__name(&sym, di->dynstr_data);
- demangled = demangle_sym(di->dso, 0, sym_name);
- if (demangled != NULL)
- sym_name = demangled;
-
- snprintf(buf, buf_sz, "%s@plt", sym_name);
-
- free(demangled);
+ if (*sym_name == '\0')
+ return false;
- return *sym_name;
+ demangled = demangle_sym(di->dso, 0, sym_name);
+ if (demangled != NULL) {
+ snprintf(buf, buf_sz, "%s@plt", demangled);
+ free(demangled);
+ } else {
+ snprintf(buf, buf_sz, "%s@plt", sym_name);
+ }
+ return true;
}
static int dso__synthesize_plt_got_symbols(struct dso *dso, Elf *elf,
--
2.40.0.348.gf938b09366-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH v1] perf symbol: Avoid use after free
2023-03-28 23:44 [PATCH v1] perf symbol: Avoid use after free Ian Rogers
@ 2023-03-29 4:52 ` Adrian Hunter
2023-03-29 5:35 ` Ian Rogers
0 siblings, 1 reply; 4+ messages in thread
From: Adrian Hunter @ 2023-03-29 4:52 UTC (permalink / raw)
To: Ian Rogers, Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Namhyung Kim,
Leo Yan, linux-perf-users, linux-kernel
On 29/03/23 02:44, Ian Rogers wrote:
> If demangling succeeds then sym_name is set to the demangled string
> that is freed. Rather than test if sym_name is empty and possibly
> use-after-free on the return path, expand out the alternatives.
Looks the same as:
https://lore.kernel.org/linux-perf-users/20230316194156.8320-2-adrian.hunter@intel.com/
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/util/symbol-elf.c | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> index c0a2de42c51b..b7e3e492bff3 100644
> --- a/tools/perf/util/symbol-elf.c
> +++ b/tools/perf/util/symbol-elf.c
> @@ -577,15 +577,17 @@ static bool get_plt_got_name(GElf_Shdr *shdr, size_t i,
> /* Get the associated symbol */
> gelf_getsym(di->dynsym_data, vr->sym_idx, &sym);
> sym_name = elf_sym__name(&sym, di->dynstr_data);
> - demangled = demangle_sym(di->dso, 0, sym_name);
> - if (demangled != NULL)
> - sym_name = demangled;
> -
> - snprintf(buf, buf_sz, "%s@plt", sym_name);
> -
> - free(demangled);
> + if (*sym_name == '\0')
> + return false;
>
> - return *sym_name;
> + demangled = demangle_sym(di->dso, 0, sym_name);
> + if (demangled != NULL) {
> + snprintf(buf, buf_sz, "%s@plt", demangled);
> + free(demangled);
> + } else {
> + snprintf(buf, buf_sz, "%s@plt", sym_name);
> + }
> + return true;
> }
>
> static int dso__synthesize_plt_got_symbols(struct dso *dso, Elf *elf,
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH v1] perf symbol: Avoid use after free
2023-03-29 4:52 ` Adrian Hunter
@ 2023-03-29 5:35 ` Ian Rogers
2023-03-29 12:53 ` Arnaldo Carvalho de Melo
0 siblings, 1 reply; 4+ messages in thread
From: Ian Rogers @ 2023-03-29 5:35 UTC (permalink / raw)
To: Adrian Hunter
Cc: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Namhyung Kim,
Leo Yan, linux-perf-users, linux-kernel
On Tue, Mar 28, 2023 at 9:52 PM Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> On 29/03/23 02:44, Ian Rogers wrote:
> > If demangling succeeds then sym_name is set to the demangled string
> > that is freed. Rather than test if sym_name is empty and possibly
> > use-after-free on the return path, expand out the alternatives.
>
> Looks the same as:
>
> https://lore.kernel.org/linux-perf-users/20230316194156.8320-2-adrian.hunter@intel.com/
Sorry for missing that. In the case it returns false, this avoids an
unnecessary snprintf.
Thanks,
Ian
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> > tools/perf/util/symbol-elf.c | 18 ++++++++++--------
> > 1 file changed, 10 insertions(+), 8 deletions(-)
> >
> > diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> > index c0a2de42c51b..b7e3e492bff3 100644
> > --- a/tools/perf/util/symbol-elf.c
> > +++ b/tools/perf/util/symbol-elf.c
> > @@ -577,15 +577,17 @@ static bool get_plt_got_name(GElf_Shdr *shdr, size_t i,
> > /* Get the associated symbol */
> > gelf_getsym(di->dynsym_data, vr->sym_idx, &sym);
> > sym_name = elf_sym__name(&sym, di->dynstr_data);
> > - demangled = demangle_sym(di->dso, 0, sym_name);
> > - if (demangled != NULL)
> > - sym_name = demangled;
> > -
> > - snprintf(buf, buf_sz, "%s@plt", sym_name);
> > -
> > - free(demangled);
> > + if (*sym_name == '\0')
> > + return false;
> >
> > - return *sym_name;
> > + demangled = demangle_sym(di->dso, 0, sym_name);
> > + if (demangled != NULL) {
> > + snprintf(buf, buf_sz, "%s@plt", demangled);
> > + free(demangled);
> > + } else {
> > + snprintf(buf, buf_sz, "%s@plt", sym_name);
> > + }
> > + return true;
> > }
> >
> > static int dso__synthesize_plt_got_symbols(struct dso *dso, Elf *elf,
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH v1] perf symbol: Avoid use after free
2023-03-29 5:35 ` Ian Rogers
@ 2023-03-29 12:53 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; 4+ messages in thread
From: Arnaldo Carvalho de Melo @ 2023-03-29 12:53 UTC (permalink / raw)
To: Ian Rogers
Cc: Adrian Hunter, Peter Zijlstra, Ingo Molnar, Mark Rutland,
Alexander Shishkin, Jiri Olsa, Namhyung Kim, Leo Yan,
linux-perf-users, linux-kernel
Em Tue, Mar 28, 2023 at 10:35:07PM -0700, Ian Rogers escreveu:
> On Tue, Mar 28, 2023 at 9:52 PM Adrian Hunter <adrian.hunter@intel.com> wrote:
> >
> > On 29/03/23 02:44, Ian Rogers wrote:
> > > If demangling succeeds then sym_name is set to the demangled string
> > > that is freed. Rather than test if sym_name is empty and possibly
> > > use-after-free on the return path, expand out the alternatives.
> >
> > Looks the same as:
> >
> > https://lore.kernel.org/linux-perf-users/20230316194156.8320-2-adrian.hunter@intel.com/
>
> Sorry for missing that. In the case it returns false, this avoids an
> unnecessary snprintf.
I applied Adrian's fixes,
- Arnaldo
> Thanks,
> Ian
>
> > >
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > > tools/perf/util/symbol-elf.c | 18 ++++++++++--------
> > > 1 file changed, 10 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> > > index c0a2de42c51b..b7e3e492bff3 100644
> > > --- a/tools/perf/util/symbol-elf.c
> > > +++ b/tools/perf/util/symbol-elf.c
> > > @@ -577,15 +577,17 @@ static bool get_plt_got_name(GElf_Shdr *shdr, size_t i,
> > > /* Get the associated symbol */
> > > gelf_getsym(di->dynsym_data, vr->sym_idx, &sym);
> > > sym_name = elf_sym__name(&sym, di->dynstr_data);
> > > - demangled = demangle_sym(di->dso, 0, sym_name);
> > > - if (demangled != NULL)
> > > - sym_name = demangled;
> > > -
> > > - snprintf(buf, buf_sz, "%s@plt", sym_name);
> > > -
> > > - free(demangled);
> > > + if (*sym_name == '\0')
> > > + return false;
> > >
> > > - return *sym_name;
> > > + demangled = demangle_sym(di->dso, 0, sym_name);
> > > + if (demangled != NULL) {
> > > + snprintf(buf, buf_sz, "%s@plt", demangled);
> > > + free(demangled);
> > > + } else {
> > > + snprintf(buf, buf_sz, "%s@plt", sym_name);
> > > + }
> > > + return true;
> > > }
> > >
> > > static int dso__synthesize_plt_got_symbols(struct dso *dso, Elf *elf,
> >
--
- Arnaldo
^ permalink raw reply [flat|nested] 4+ messages in thread
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2023-03-28 23:44 [PATCH v1] perf symbol: Avoid use after free Ian Rogers
2023-03-29 4:52 ` Adrian Hunter
2023-03-29 5:35 ` Ian Rogers
2023-03-29 12:53 ` Arnaldo Carvalho de Melo
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