Commit 4d74ecf6 authored Apr 25, 2018 by John Fastabend Committed by Greg Kroah-Hartman Jul 03, 2018

bpf: fix uninitialized variable in bpf tools



[ Upstream commit 815425567dea6c54494e85050631d6bdda907c5d ]

Here the variable cont is used as the saved_pointer for a call to
strtok_r(). It is safe to use the value uninitialized in this
context however and the later reference is only ever used if
the strtok_r is successful. But, 'gcc-5' at least doesn't have all
this knowledge so initialize cont to NULL. Additionally, do the
natural NULL check before accessing just for completness.

The warning is the following:

./bpf/tools/bpf/bpf_dbg.c: In function ‘cmd_load’:
./bpf/tools/bpf/bpf_dbg.c:1077:13: warning: ‘cont’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  } else if (matches(subcmd, "pcap") == 0) {

Fixes: fd981e3c "filter: bpf_dbg: add minimal bpf debugger"
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 3332858e

tools/net/bpf_dbg.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -1063,7 +1063,7 @@ static int cmd_load_pcap(char *file)

		static int cmd_load(char *arg)
		{
		char subcmd, cont, *tmp = strdup(arg);
		char subcmd, cont = NULL, *tmp = strdup(arg);
		int ret = CMD_OK;

		subcmd = strtok_r(tmp, " ", &cont);
		@@ -1073,6 +1073,9 @@ static int cmd_load(char *arg)
		bpf_reset();
		bpf_reset_breakpoints();

		if (!cont)
		ret = CMD_ERR;
		else
		ret = cmd_load_bpf(cont);
		} else if (matches(subcmd, "pcap") == 0) {
		ret = cmd_load_pcap(cont);