* [PATCH] perf/core: use strndup_user() instead of buggy open-coded version
@ 2019-02-18 22:07 Jann Horn
2019-02-19 11:45 ` Masami Hiramatsu
0 siblings, 1 reply; 5+ messages in thread
From: Jann Horn @ 2019-02-18 22:07 UTC (permalink / raw)
To: Ingo Molnar, Steven Rostedt, jannh
Cc: linux-kernel, Song Liu, Masami Hiramatsu
The first version of this method was missing the check for
`ret == PATH_MAX`; then such a check was added, but it didn't call kfree()
on error, so there was still a small memory leak in the error case.
Fix it by using strndup_user() instead of open-coding it.
Fixes: 0eadcc7a7bc0 ("perf/core: Fix perf_uprobe_init()")
Signed-off-by: Jann Horn <jannh@google.com>
---
compile-tested only
kernel/trace/trace_event_perf.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 76217bbef815..c744b02081c3 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -299,15 +299,11 @@ int perf_uprobe_init(struct perf_event *p_event,
if (!p_event->attr.uprobe_path)
return -EINVAL;
- path = kzalloc(PATH_MAX, GFP_KERNEL);
- if (!path)
- return -ENOMEM;
- ret = strncpy_from_user(
- path, u64_to_user_ptr(p_event->attr.uprobe_path), PATH_MAX);
- if (ret == PATH_MAX)
- return -E2BIG;
- if (ret < 0)
- goto out;
+
+ path = strndup_user(u64_to_user_ptr(p_event->attr.uprobe_path),
+ PATH_MAX);
+ if (IS_ERR(path))
+ return PTR_ERR(path);
if (path[0] == '\0') {
ret = -EINVAL;
goto out;
--
2.21.0.rc0.258.g878e2cd30e-goog
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] perf/core: use strndup_user() instead of buggy open-coded version
2019-02-18 22:07 [PATCH] perf/core: use strndup_user() instead of buggy open-coded version Jann Horn
@ 2019-02-19 11:45 ` Masami Hiramatsu
2019-02-19 14:51 ` Masami Hiramatsu
0 siblings, 1 reply; 5+ messages in thread
From: Masami Hiramatsu @ 2019-02-19 11:45 UTC (permalink / raw)
To: Jann Horn
Cc: Ingo Molnar, Steven Rostedt, linux-kernel, Song Liu, Masami Hiramatsu
On Mon, 18 Feb 2019 23:07:23 +0100
Jann Horn <jannh@google.com> wrote:
> The first version of this method was missing the check for
> `ret == PATH_MAX`; then such a check was added, but it didn't call kfree()
> on error, so there was still a small memory leak in the error case.
> Fix it by using strndup_user() instead of open-coding it.
>
This looks good to me.
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Thank you!
> Fixes: 0eadcc7a7bc0 ("perf/core: Fix perf_uprobe_init()")
> Signed-off-by: Jann Horn <jannh@google.com>
> ---
> compile-tested only
>
> kernel/trace/trace_event_perf.c | 14 +++++---------
> 1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
> index 76217bbef815..c744b02081c3 100644
> --- a/kernel/trace/trace_event_perf.c
> +++ b/kernel/trace/trace_event_perf.c
> @@ -299,15 +299,11 @@ int perf_uprobe_init(struct perf_event *p_event,
>
> if (!p_event->attr.uprobe_path)
> return -EINVAL;
> - path = kzalloc(PATH_MAX, GFP_KERNEL);
> - if (!path)
> - return -ENOMEM;
> - ret = strncpy_from_user(
> - path, u64_to_user_ptr(p_event->attr.uprobe_path), PATH_MAX);
> - if (ret == PATH_MAX)
> - return -E2BIG;
> - if (ret < 0)
> - goto out;
> +
> + path = strndup_user(u64_to_user_ptr(p_event->attr.uprobe_path),
> + PATH_MAX);
> + if (IS_ERR(path))
> + return PTR_ERR(path);
> if (path[0] == '\0') {
> ret = -EINVAL;
> goto out;
> --
> 2.21.0.rc0.258.g878e2cd30e-goog
>
--
Masami Hiramatsu <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] perf/core: use strndup_user() instead of buggy open-coded version
2019-02-19 11:45 ` Masami Hiramatsu
@ 2019-02-19 14:51 ` Masami Hiramatsu
2019-02-20 15:19 ` Jann Horn
0 siblings, 1 reply; 5+ messages in thread
From: Masami Hiramatsu @ 2019-02-19 14:51 UTC (permalink / raw)
To: Masami Hiramatsu
Cc: Jann Horn, Ingo Molnar, Steven Rostedt, linux-kernel, Song Liu
On Tue, 19 Feb 2019 20:45:02 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:
> On Mon, 18 Feb 2019 23:07:23 +0100
> Jann Horn <jannh@google.com> wrote:
>
> > The first version of this method was missing the check for
> > `ret == PATH_MAX`; then such a check was added, but it didn't call kfree()
> > on error, so there was still a small memory leak in the error case.
> > Fix it by using strndup_user() instead of open-coding it.
> >
>
> This looks good to me.
>
> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
BTW, I think it should note that if the string is longer than PATH_MAX.
caller will receive -EINVAL instead of -E2BIG with this fix.
Thank you,
>
> Thank you!
>
> > Fixes: 0eadcc7a7bc0 ("perf/core: Fix perf_uprobe_init()")
> > Signed-off-by: Jann Horn <jannh@google.com>
> > ---
> > compile-tested only
> >
> > kernel/trace/trace_event_perf.c | 14 +++++---------
> > 1 file changed, 5 insertions(+), 9 deletions(-)
> >
> > diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
> > index 76217bbef815..c744b02081c3 100644
> > --- a/kernel/trace/trace_event_perf.c
> > +++ b/kernel/trace/trace_event_perf.c
> > @@ -299,15 +299,11 @@ int perf_uprobe_init(struct perf_event *p_event,
> >
> > if (!p_event->attr.uprobe_path)
> > return -EINVAL;
> > - path = kzalloc(PATH_MAX, GFP_KERNEL);
> > - if (!path)
> > - return -ENOMEM;
> > - ret = strncpy_from_user(
> > - path, u64_to_user_ptr(p_event->attr.uprobe_path), PATH_MAX);
> > - if (ret == PATH_MAX)
> > - return -E2BIG;
> > - if (ret < 0)
> > - goto out;
> > +
> > + path = strndup_user(u64_to_user_ptr(p_event->attr.uprobe_path),
> > + PATH_MAX);
> > + if (IS_ERR(path))
> > + return PTR_ERR(path);
> > if (path[0] == '\0') {
> > ret = -EINVAL;
> > goto out;
> > --
> > 2.21.0.rc0.258.g878e2cd30e-goog
> >
>
>
> --
> Masami Hiramatsu <mhiramat@kernel.org>
--
Masami Hiramatsu <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] perf/core: use strndup_user() instead of buggy open-coded version
2019-02-19 14:51 ` Masami Hiramatsu
@ 2019-02-20 15:19 ` Jann Horn
2019-02-20 16:00 ` Masami Hiramatsu
0 siblings, 1 reply; 5+ messages in thread
From: Jann Horn @ 2019-02-20 15:19 UTC (permalink / raw)
To: Masami Hiramatsu; +Cc: Ingo Molnar, Steven Rostedt, kernel list, Song Liu
On Tue, Feb 19, 2019 at 3:51 PM Masami Hiramatsu <mhiramat@kernel.org> wrote:
> On Tue, 19 Feb 2019 20:45:02 +0900
> Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> > On Mon, 18 Feb 2019 23:07:23 +0100
> > Jann Horn <jannh@google.com> wrote:
> >
> > > The first version of this method was missing the check for
> > > `ret == PATH_MAX`; then such a check was added, but it didn't call kfree()
> > > on error, so there was still a small memory leak in the error case.
> > > Fix it by using strndup_user() instead of open-coding it.
> > >
> >
> > This looks good to me.
> >
> > Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
>
> BTW, I think it should note that if the string is longer than PATH_MAX.
> caller will receive -EINVAL instead of -E2BIG with this fix.
Oh, whoops, I hadn't noticed that.
Do you want me to just add a note to the changelog, or do I have to
work around this in the code?
> > > Fixes: 0eadcc7a7bc0 ("perf/core: Fix perf_uprobe_init()")
> > > Signed-off-by: Jann Horn <jannh@google.com>
> > > ---
> > > compile-tested only
> > >
> > > kernel/trace/trace_event_perf.c | 14 +++++---------
> > > 1 file changed, 5 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
> > > index 76217bbef815..c744b02081c3 100644
> > > --- a/kernel/trace/trace_event_perf.c
> > > +++ b/kernel/trace/trace_event_perf.c
> > > @@ -299,15 +299,11 @@ int perf_uprobe_init(struct perf_event *p_event,
> > >
> > > if (!p_event->attr.uprobe_path)
> > > return -EINVAL;
> > > - path = kzalloc(PATH_MAX, GFP_KERNEL);
> > > - if (!path)
> > > - return -ENOMEM;
> > > - ret = strncpy_from_user(
> > > - path, u64_to_user_ptr(p_event->attr.uprobe_path), PATH_MAX);
> > > - if (ret == PATH_MAX)
> > > - return -E2BIG;
> > > - if (ret < 0)
> > > - goto out;
> > > +
> > > + path = strndup_user(u64_to_user_ptr(p_event->attr.uprobe_path),
> > > + PATH_MAX);
> > > + if (IS_ERR(path))
> > > + return PTR_ERR(path);
> > > if (path[0] == '\0') {
> > > ret = -EINVAL;
> > > goto out;
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] perf/core: use strndup_user() instead of buggy open-coded version
2019-02-20 15:19 ` Jann Horn
@ 2019-02-20 16:00 ` Masami Hiramatsu
0 siblings, 0 replies; 5+ messages in thread
From: Masami Hiramatsu @ 2019-02-20 16:00 UTC (permalink / raw)
To: Jann Horn; +Cc: Ingo Molnar, Steven Rostedt, kernel list, Song Liu
Hi Jann,
On Wed, 20 Feb 2019 16:19:10 +0100
Jann Horn <jannh@google.com> wrote:
> On Tue, Feb 19, 2019 at 3:51 PM Masami Hiramatsu <mhiramat@kernel.org> wrote:
> > On Tue, 19 Feb 2019 20:45:02 +0900
> > Masami Hiramatsu <mhiramat@kernel.org> wrote:
> >
> > > On Mon, 18 Feb 2019 23:07:23 +0100
> > > Jann Horn <jannh@google.com> wrote:
> > >
> > > > The first version of this method was missing the check for
> > > > `ret == PATH_MAX`; then such a check was added, but it didn't call kfree()
> > > > on error, so there was still a small memory leak in the error case.
> > > > Fix it by using strndup_user() instead of open-coding it.
> > > >
> > >
> > > This looks good to me.
> > >
> > > Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
> >
> > BTW, I think it should note that if the string is longer than PATH_MAX.
> > caller will receive -EINVAL instead of -E2BIG with this fix.
>
> Oh, whoops, I hadn't noticed that.
>
> Do you want me to just add a note to the changelog, or do I have to
> work around this in the code?
I think work around will be good if this goes to stable, since I guess
this return code may go to user space.
Thank you,
>
> > > > Fixes: 0eadcc7a7bc0 ("perf/core: Fix perf_uprobe_init()")
> > > > Signed-off-by: Jann Horn <jannh@google.com>
> > > > ---
> > > > compile-tested only
> > > >
> > > > kernel/trace/trace_event_perf.c | 14 +++++---------
> > > > 1 file changed, 5 insertions(+), 9 deletions(-)
> > > >
> > > > diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
> > > > index 76217bbef815..c744b02081c3 100644
> > > > --- a/kernel/trace/trace_event_perf.c
> > > > +++ b/kernel/trace/trace_event_perf.c
> > > > @@ -299,15 +299,11 @@ int perf_uprobe_init(struct perf_event *p_event,
> > > >
> > > > if (!p_event->attr.uprobe_path)
> > > > return -EINVAL;
> > > > - path = kzalloc(PATH_MAX, GFP_KERNEL);
> > > > - if (!path)
> > > > - return -ENOMEM;
> > > > - ret = strncpy_from_user(
> > > > - path, u64_to_user_ptr(p_event->attr.uprobe_path), PATH_MAX);
> > > > - if (ret == PATH_MAX)
> > > > - return -E2BIG;
> > > > - if (ret < 0)
> > > > - goto out;
> > > > +
> > > > + path = strndup_user(u64_to_user_ptr(p_event->attr.uprobe_path),
> > > > + PATH_MAX);
> > > > + if (IS_ERR(path))
> > > > + return PTR_ERR(path);
> > > > if (path[0] == '\0') {
> > > > ret = -EINVAL;
> > > > goto out;
--
Masami Hiramatsu <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 5+ messages in thread
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2019-02-18 22:07 [PATCH] perf/core: use strndup_user() instead of buggy open-coded version Jann Horn
2019-02-19 11:45 ` Masami Hiramatsu
2019-02-19 14:51 ` Masami Hiramatsu
2019-02-20 15:19 ` Jann Horn
2019-02-20 16:00 ` Masami Hiramatsu
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