linux-kernel - Re: [PATCH] tracing/probe: fix memleak in fetch_op

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Date:   Tue, 16 Jun 2020 17:46:47 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@...il.com>,
        mingo@...hat.com, linux-kernel@...r.kernel.org,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>, oleg@...hat.com
Subject: Re: [PATCH] tracing/probe: fix memleak in fetch_op_data operations

Hi Steve,

On Mon, 15 Jun 2020 17:13:37 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:

> 
> Masami or Srikar would you like to look at this patch.

Thanks for letting me know!

> 
> And wondering why you were not on the Cc to this patch in the first
> place, please take a look at the patch I want to add at the bottom ;-)

Agreed to expand MAINTAINERS to clarify that. For the kprobes part, 

Acked-by: Masami Hiramatsu <mhiramat@...nel.org>

BTW, for uprobes, I think Oleg is mainly reviewed changes on that in
these days. Maybe better to assign him?

Thanks,


> 
> 
> On Mon, 15 Jun 2020 20:00:38 +0530
> Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@...il.com> wrote:
> 
> > kmemleak report:
> >     [<57dcc2ca>] __kmalloc_track_caller+0x139/0x2b0
> >     [<f1c45d0f>] kstrndup+0x37/0x80
> >     [<f9761eb0>] parse_probe_arg.isra.7+0x3cc/0x630
> >     [<055bf2ba>] traceprobe_parse_probe_arg+0x2f5/0x810
> >     [<655a7766>] trace_kprobe_create+0x2ca/0x950
> >     [<4fc6a02a>] create_or_delete_trace_kprobe+0xf/0x30
> >     [<6d1c8a52>] trace_run_command+0x67/0x80
> >     [<be812cc0>] trace_parse_run_command+0xa7/0x140
> >     [<aecfe401>] probes_write+0x10/0x20
> >     [<2027641c>] __vfs_write+0x30/0x1e0
> >     [<6a4aeee1>] vfs_write+0x96/0x1b0
> >     [<3517fb7d>] ksys_write+0x53/0xc0
> >     [<dad91db7>] __ia32_sys_write+0x15/0x20
> >     [<da347f64>] do_syscall_32_irqs_on+0x3d/0x260
> >     [<fd0b7e7d>] do_fast_syscall_32+0x39/0xb0
> >     [<ea5ae810>] entry_SYSENTER_32+0xaf/0x102
> > 
> > Post parse_probe_arg(), the FETCH_OP_DATA operation type is overwritten
> > to FETCH_OP_ST_STRING, as a result memory is never freed since
> > traceprobe_free_probe_arg() iterates only over SYMBOL and DATA op types
> > 
> > Setup fetch string operation correctly after fetch_op_data operation.
> > 
> > Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@...il.com>
> > ---
> >  kernel/trace/trace_probe.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> > index b8a928e..d2867cc 100644
> > --- a/kernel/trace/trace_probe.c
> > +++ b/kernel/trace/trace_probe.c
> > @@ -639,8 +639,8 @@ static int traceprobe_parse_probe_arg_body(char *arg, ssize_t *size,
> >  			ret = -EINVAL;
> >  			goto fail;
> >  		}
> > -		if ((code->op == FETCH_OP_IMM || code->op == FETCH_OP_COMM) ||
> > -		     parg->count) {
> > +		if ((code->op == FETCH_OP_IMM || code->op == FETCH_OP_COMM ||
> > +		     code->op == FETCH_OP_DATA) || parg->count) {
> >  			/*
> >  			 * IMM, DATA and COMM is pointing actual address, those
> >  			 * must be kept, and if parg->count != 0, this is an
> 
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 47873f2e6696..116e5cc7ef95 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9229,6 +9229,8 @@ F:	Documentation/kprobes.txt
>  F:	include/linux/kprobes.h
>  F:	include/asm-generic/kprobes.h
>  F:	kernel/kprobes.c
> +F:	kernel/trace/trace_kprobe.c
> +F:	kernel/trace/trace_probe.c
>  
>  KS0108 LCD CONTROLLER DRIVER
>  M:	Miguel Ojeda Sandonis <miguel.ojeda.sandonis@...il.com>
> @@ -16996,6 +16998,16 @@ F:	drivers/mtd/ubi/
>  F:	include/linux/mtd/ubi.h
>  F:	include/uapi/mtd/ubi-user.h
>  
> +UPROBES
> +M:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
> +S:	Maintained
> +F:	Documentation/trace/uprobetracer.rst
> +F:	Documentation/features/debug/uprobes
> +F:	include/linux/uprobes.h
> +F:	kernel/events/uprobes.c
> +F:	kernel/trace/trace_uprobe.c
> +F:	kernel/trace/trace_probe.c
> +
>  USB "USBNET" DRIVER FRAMEWORK
>  M:	Oliver Neukum <oneukum@...e.com>
>  L:	netdev@...r.kernel.org
> 
> 
> -- Steve


-- 
Masami Hiramatsu <mhiramat@...nel.org>