[PATCH AUTOSEL 4.19 195/219] bpf: decrease usercnt if bpf_map_new_fd() fails in bpf_map_get_fd_by_id()

[Sasha Levin]

From: Peng Sun <sironhide0null@xxxxxxxxx>

[ Upstream commit 781e62823cb81b972dc8652c1827205cda2ac9ac ]

In bpf/syscall.c, bpf_map_get_fd_by_id() use bpf_map_inc_not_zero()
to increase the refcount, both map->refcnt and map->usercnt. Then, if
bpf_map_new_fd() fails, should handle map->usercnt too.

Fixes: bd5f5f4ecb78 ("bpf: Add BPF_MAP_GET_FD_BY_ID")
Signed-off-by: Peng Sun <sironhide0null@xxxxxxxxx>
Acked-by: Martin KaFai Lau <kafai@xxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 kernel/bpf/syscall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 6e544e364821e..90bb0c05c10e9 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1887,7 +1887,7 @@ static int bpf_map_get_fd_by_id(const union bpf_attr *attr)
 
 	fd = bpf_map_new_fd(map, f_flags);
 	if (fd < 0)
-		bpf_map_put(map);
+		bpf_map_put_with_uref(map);
 
 	return fd;
 }
-- 
2.20.1