Commit 50b796e6 authored by Kumar Kartikeya Dwivedi's avatar Kumar Kartikeya Dwivedi Committed by Alexei Starovoitov
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samples: bpf: Fix a couple of warnings 



cookie_uid_helper_example.c: In function ‘main’:
cookie_uid_helper_example.c:178:69: warning: ‘ -j ACCEPT’ directive
	writing 10 bytes into a region of size between 8 and 58
	[-Wformat-overflow=]
  178 |  sprintf(rules, "iptables -A OUTPUT -m bpf --object-pinned %s -j ACCEPT",
      |								       ^~~~~~~~~~
/home/kkd/src/linux/samples/bpf/cookie_uid_helper_example.c:178:9: note:
	‘sprintf’ output between 53 and 103 bytes into a destination of size 100
  178 |  sprintf(rules, "iptables -A OUTPUT -m bpf --object-pinned %s -j ACCEPT",
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  179 |         file);
      |         ~~~~~

Fix by using snprintf and a sufficiently sized buffer.

tracex4_user.c:35:15: warning: ‘write’ reading 12 bytes from a region of
	size 11 [-Wstringop-overread]
   35 |         key = write(1, "\e[1;1H\e[2J", 12); /* clear screen */
      |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

Use size as 11.

Signed-off-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210821002010.845777-2-memxor@gmail.com
parent d7af7e49

samples/bpf/cookie_uid_helper_example.c

+8 −3
Original line number Diff line number Diff line
@@ -167,7 +167,7 @@ static void prog_load(void) 
static void prog_attach_iptables(char *file)

{

	int ret;

	char rules[100];

	char rules[256];



	if (bpf_obj_pin(prog_fd, file))

		error(1, errno, "bpf_obj_pin");
@@ -175,8 +175,13 @@ static void prog_attach_iptables(char *file) 
		printf("file path too long: %s\n", file);

		exit(1);

	}

	sprintf(rules, "iptables -A OUTPUT -m bpf --object-pinned %s -j ACCEPT",

	ret = snprintf(rules, sizeof(rules),

		       "iptables -A OUTPUT -m bpf --object-pinned %s -j ACCEPT",

		       file);

	if (ret < 0 || ret >= sizeof(rules)) {

		printf("error constructing iptables command\n");

		exit(1);

	}

	ret = system(rules);

	if (ret < 0) {

		printf("iptables rule update failed: %d/n", WEXITSTATUS(ret));

samples/bpf/tracex4_user.c

+1 −1
Original line number Diff line number Diff line
@@ -32,7 +32,7 @@ static void print_old_objects(int fd) 
	__u64 key, next_key;

	struct pair v;



	key = write(1, "\e[1;1H\e[2J", 12); /* clear screen */

	key = write(1, "\e[1;1H\e[2J", 11); /* clear screen */



	key = -1;

	while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {