[PATCH AUTOSEL 4.19 058/123] tools: bpftool: fix potential NULL pointer dereference in do_load

Sasha Levin
2018-12-05T09:39:21Z

From: Jakub Kicinski <jakub.kicinski@netronome.com>

[ Upstream commit dde7011a824cfa815b03f853ec985ff46b740939 ]

This patch fixes a possible null pointer dereference in
do_load, detected by the semantic patch deref_null.cocci,
with the following warning:

./tools/bpf/bpftool/prog.c:1021:23-25: ERROR: map_replace is NULL but dereferenced.

The following code has potential null pointer references:
881 map_replace = reallocarray(map_replace, old_map_fds + 1,
882 sizeof(*map_replace));
883 if (!map_replace) {
884 p_err("mem alloc failed");
885 goto err_free_reuse_maps;
886 }

...
1019 err_free_reuse_maps:
1020 for (i = 0; i < old_map_fds; i++)
1021 close(map_replace[i].fd);
1022 free(map_replace);

Fixes: 3ff5a4dc5d89 ("tools: bpftool: allow reuse of maps with bpftool prog load")
Co-developed-by: Wen Yang <wen.yang99@zte.com.cn>
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/bpf/bpftool/prog.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index dce960d22106..0de024a6cc2b 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -749,6 +749,7 @@ static int do_load(int argc, char **argv)
}
NEXT_ARG();
} else if (is_prefix(*argv, "map")) {
+ void *new_map_replace;
char *endptr, *name;
int fd;

@@ -782,12 +783,15 @@ static int do_load(int argc, char **argv)
if (fd < 0)
goto err_free_reuse_maps;

- map_replace = reallocarray(map_replace, old_map_fds + 1,
- sizeof(*map_replace));
- if (!map_replace) {
+ new_map_replace = reallocarray(map_replace,
+ old_map_fds + 1,
+ sizeof(*map_replace));
+ if (!new_map_replace) {
p_err("mem alloc failed");
goto err_free_reuse_maps;
}
+ map_replace = new_map_replace;
+
map_replace[old_map_fds].idx = idx;
map_replace[old_map_fds].name = name;
map_replace[old_map_fds].fd = fd;
--
2.17.1