[for-linus][PATCH 11/17] tracing/probe: Fix memleak in fetch_op_data operations

Steven Rostedt
2020-06-18T23:56:59Z

From: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>

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.

Link: https://lkml.kernel.org/r/20200615143034.GA1734@cosmos

Cc: stable@vger.kernel.org
Fixes: a42e3c4de964 ("tracing/probe: Add immediate string parameter support")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
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 b8a928e925c7..d2867ccc6aca 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
--
2.26.2