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

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Message-ID: <20200615171337.6525cefa@oasis.local.home>
Date:   Mon, 15 Jun 2020 17:13:37 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@...il.com>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Subject: Re: [PATCH] tracing/probe: fix memleak in fetch_op_data operations


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

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 ;-)


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