samples, bpf: fix to change the buffer size for read()
[ Upstream commit f7c2d64bac1be2ff32f8e4f500c6e5429c1003e0 ]
If the trace for read is larger than 4096, the return
value sz will be 4096. This results in off-by-one error
on buf:
static char buf[4096];
ssize_t sz;
sz = read(trace_fd, buf, sizeof(buf));
if (sz > 0) {
buf[sz] = 0;
puts(buf);
}
Signed-off-by: Chang-Hsien Tsai <luke.tw@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
index 97913e1..99e5a2f 100644
--- a/samples/bpf/bpf_load.c
+++ b/samples/bpf/bpf_load.c
@@ -369,7 +369,7 @@
static char buf[4096];
ssize_t sz;
- sz = read(trace_fd, buf, sizeof(buf));
+ sz = read(trace_fd, buf, sizeof(buf) - 1);
if (sz > 0) {
buf[sz] = 0;
puts(buf);