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[PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not found

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  [PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not found He Kuang <hekuang@huawei.com> - 2016-06-22 09:00 +0200
    Re: [PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not  found "Wangnan (F)" <wangnan0@huawei.com> - 2016-06-23 04:10 +0200
      Re: [PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not  found Hekuang <hekuang@huawei.com> - 2016-06-23 05:10 +0200
      Re: [PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not  found Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-06-23 14:10 +0200
        Re: [PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not  found Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-06-23 15:30 +0200

#1428467 — [PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not found

We should check if 'dso' is a null pointer before passing it to the
function dso__type(), otherwise a segfault will be raised in
dso__data_get_fd(). In function machine__find_vdso(), the return value
checking of 'dso' is missed and this patch fixes this issue.

Signed-off-by: He Kuang <hekuang@huawei.com>
---
 tools/perf/util/vdso.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c
index 8f81c41..7bdcad4 100644
--- a/tools/perf/util/vdso.c
+++ b/tools/perf/util/vdso.c
@@ -296,7 +296,7 @@ static struct dso *machine__find_vdso(struct machine *machine,
 		if (!dso) {
 			dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
 					   true);
-			if (dso_type != dso__type(dso, machine))
+			if (dso && dso_type != dso__type(dso, machine))
 				dso = NULL;
 		}
 		break;
-- 
1.8.5.2

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#1429400 — Re: [PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not found

Hi,

This patch fixes a real crash problem when we do 'perf report'
on an arm64 platform with arm32 program.
It is introduced by commit f9b2bdf228 ("perf tools: Find vdso
with the consider of cross-platform"). From dmesg report, perf
crashes in dso__type() because dso is NULL.

Still don't know why on x86 it never crash, but it is obviously
that we need to check the return vaule from __dso__find(): it can
be NULL.

So please consider pulling.

Thank you.

On 2016/6/22 14:57, He Kuang wrote:
> We should check if 'dso' is a null pointer before passing it to the
> function dso__type(), otherwise a segfault will be raised in
> dso__data_get_fd(). In function machine__find_vdso(), the return value
> checking of 'dso' is missed and this patch fixes this issue.
>
> Signed-off-by: He Kuang <hekuang@huawei.com>
> ---
>   tools/perf/util/vdso.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c
> index 8f81c41..7bdcad4 100644
> --- a/tools/perf/util/vdso.c
> +++ b/tools/perf/util/vdso.c
> @@ -296,7 +296,7 @@ static struct dso *machine__find_vdso(struct machine *machine,
>   		if (!dso) {
>   			dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
>   					   true);
> -			if (dso_type != dso__type(dso, machine))
> +			if (dso && dso_type != dso__type(dso, machine))
>   				dso = NULL;
>   		}
>   		break;

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#1429422 — Re: [PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not found

在 2016/6/23 10:02, Wangnan (F) 写道:
> Hi,
>
> This patch fixes a real crash problem when we do 'perf report'
> on an arm64 platform with arm32 program.
> It is introduced by commit f9b2bdf228 ("perf tools: Find vdso
> with the consider of cross-platform"). From dmesg report, perf
> crashes in dso__type() because dso is NULL.
>
> Still don't know why on x86 it never crash, but it is obviously

This is because the fault only occured while
dso_type==DSO__TYPE_32BIT, run 64bit executable won't enter the
fault branch, but if we run a 32bit executable on x86_64, this
bug can be reproduced easily.

   # file ~/hello
   ~/hello: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), 
dynamically linked (uses shared libs), for GNU/Linux 4.5.0, not stripped

   # perf record -g hello
   Segmentation fault

Thank you.

> that we need to check the return vaule from __dso__find(): it can
> be NULL.
>
> So please consider pulling.
>
> Thank you.
>
> On 2016/6/22 14:57, He Kuang wrote:
>> We should check if 'dso' is a null pointer before passing it to the
>> function dso__type(), otherwise a segfault will be raised in
>> dso__data_get_fd(). In function machine__find_vdso(), the return value
>> checking of 'dso' is missed and this patch fixes this issue.
>>
>> Signed-off-by: He Kuang <hekuang@huawei.com>
>> ---
>>   tools/perf/util/vdso.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c
>> index 8f81c41..7bdcad4 100644
>> --- a/tools/perf/util/vdso.c
>> +++ b/tools/perf/util/vdso.c
>> @@ -296,7 +296,7 @@ static struct dso *machine__find_vdso(struct 
>> machine *machine,
>>           if (!dso) {
>>               dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
>>                          true);
>> -            if (dso_type != dso__type(dso, machine))
>> +            if (dso && dso_type != dso__type(dso, machine))
>>                   dso = NULL;
>>           }
>>           break;
>
>
>

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#1429737 — Re: [PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not found

Em Thu, Jun 23, 2016 at 10:02:39AM +0800, Wangnan (F) escreveu:
> Hi,
> 
> This patch fixes a real crash problem when we do 'perf report'
> on an arm64 platform with arm32 program.
> It is introduced by commit f9b2bdf228 ("perf tools: Find vdso
> with the consider of cross-platform"). From dmesg report, perf
> crashes in dso__type() because dso is NULL.

Ok, I removed f9b2bdf228 because of this crash, Ingo reported it, now
that I see this new patch and checked that the crash was introduced by
f9b2bdf228 I'll just combine those two and test again using a 32-bit
hackbench on top of f9b2bdf228, to reproduce the crash, then on top of
both patches combined.

- Arnaldo
 
> Still don't know why on x86 it never crash, but it is obviously
> that we need to check the return vaule from __dso__find(): it can
> be NULL.
> 
> So please consider pulling.
> 
> Thank you.
> 
> On 2016/6/22 14:57, He Kuang wrote:
> > We should check if 'dso' is a null pointer before passing it to the
> > function dso__type(), otherwise a segfault will be raised in
> > dso__data_get_fd(). In function machine__find_vdso(), the return value
> > checking of 'dso' is missed and this patch fixes this issue.
> > 
> > Signed-off-by: He Kuang <hekuang@huawei.com>
> > ---
> >   tools/perf/util/vdso.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c
> > index 8f81c41..7bdcad4 100644
> > --- a/tools/perf/util/vdso.c
> > +++ b/tools/perf/util/vdso.c
> > @@ -296,7 +296,7 @@ static struct dso *machine__find_vdso(struct machine *machine,
> >   		if (!dso) {
> >   			dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
> >   					   true);
> > -			if (dso_type != dso__type(dso, machine))
> > +			if (dso && dso_type != dso__type(dso, machine))
> >   				dso = NULL;
> >   		}
> >   		break;
> 

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#1429828 — Re: [PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not found

Em Thu, Jun 23, 2016 at 09:07:04AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Thu, Jun 23, 2016 at 10:02:39AM +0800, Wangnan (F) escreveu:
> > Hi,
> > 
> > This patch fixes a real crash problem when we do 'perf report'
> > on an arm64 platform with arm32 program.
> > It is introduced by commit f9b2bdf228 ("perf tools: Find vdso
> > with the consider of cross-platform"). From dmesg report, perf
> > crashes in dso__type() because dso is NULL.
> 
> Ok, I removed f9b2bdf228 because of this crash, Ingo reported it, now
> that I see this new patch and checked that the crash was introduced by
> f9b2bdf228 I'll just combine those two and test again using a 32-bit
> hackbench on top of f9b2bdf228, to reproduce the crash, then on top of
> both patches combined.

Tested, reproduced, ammended, fixed, applied, thanks!

- Arnaldo
 
> - Arnaldo
>  
> > Still don't know why on x86 it never crash, but it is obviously
> > that we need to check the return vaule from __dso__find(): it can
> > be NULL.
> > 
> > So please consider pulling.
> > 
> > Thank you.
> > 
> > On 2016/6/22 14:57, He Kuang wrote:
> > > We should check if 'dso' is a null pointer before passing it to the
> > > function dso__type(), otherwise a segfault will be raised in
> > > dso__data_get_fd(). In function machine__find_vdso(), the return value
> > > checking of 'dso' is missed and this patch fixes this issue.
> > > 
> > > Signed-off-by: He Kuang <hekuang@huawei.com>
> > > ---
> > >   tools/perf/util/vdso.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c
> > > index 8f81c41..7bdcad4 100644
> > > --- a/tools/perf/util/vdso.c
> > > +++ b/tools/perf/util/vdso.c
> > > @@ -296,7 +296,7 @@ static struct dso *machine__find_vdso(struct machine *machine,
> > >   		if (!dso) {
> > >   			dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
> > >   					   true);
> > > -			if (dso_type != dso__type(dso, machine))
> > > +			if (dso && dso_type != dso__type(dso, machine))
> > >   				dso = NULL;
> > >   		}
> > >   		break;
> > 

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