From: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Date: Sat, 21 Aug 2021 05:49:49 +0530
Subject: samples: bpf: Fix a couple of warnings
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Patch-mainline: v5.15-rc1
Git-commit: 50b796e645a5d217fd9d8648ec594241e6f1dd57
References: jsc#PED-1377
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: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210821002010.845777-2-memxor@gmail.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
samples/bpf/cookie_uid_helper_example.c | 11 ++++++++---
samples/bpf/tracex4_user.c | 2 +-
2 files changed, 9 insertions(+), 4 deletions(-)
--- a/samples/bpf/cookie_uid_helper_example.c
+++ b/samples/bpf/cookie_uid_helper_example.c
@@ -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 *f
printf("file path too long: %s\n", file);
exit(1);
}
- sprintf(rules, "iptables -A OUTPUT -m bpf --object-pinned %s -j ACCEPT",
- file);
+ 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));
--- a/samples/bpf/tracex4_user.c
+++ b/samples/bpf/tracex4_user.c
@@ -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) {