[PATCH AUTOSEL 5.7 36/60] bpf: Fix fds_example SIGSEGV error

Sasha Levin
2020-08-10T19:28:06Z

From: Wenbo Zhang <ethercflow@gmail.com>

[ Upstream commit eef8a42d6ce087d1c81c960ae0d14f955b742feb ]

The `BPF_LOG_BUF_SIZE`'s value is `UINT32_MAX >> 8`, so define an array
with it on stack caused an overflow.

Signed-off-by: Wenbo Zhang <ethercflow@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200710092035.28919-1-ethercflow@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
samples/bpf/fds_example.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/samples/bpf/fds_example.c b/samples/bpf/fds_example.c
index d5992f7872328..59f45fef51109 100644
--- a/samples/bpf/fds_example.c
+++ b/samples/bpf/fds_example.c
@@ -30,6 +30,8 @@
#define BPF_M_MAP 1
#define BPF_M_PROG 2

+char bpf_log_buf[BPF_LOG_BUF_SIZE];
+
static void usage(void)
{
printf("Usage: fds_example [...]\n");
@@ -57,7 +59,6 @@ static int bpf_prog_create(const char *object)
BPF_EXIT_INSN(),
};
size_t insns_cnt = sizeof(insns) / sizeof(struct bpf_insn);
- char bpf_log_buf[BPF_LOG_BUF_SIZE];
struct bpf_object *obj;
int prog_fd;

--
2.25.1