bpf: fix refcnt overflow
On a system with >32Gbyte of phyiscal memory and infinite RLIMIT_MEMLOCK,
the malicious application may overflow 32-bit bpf program refcnt.
It's also possible to overflow map refcnt on 1Tb system.
Impose 32k hard limit which means that the same bpf program or
map cannot be shared by more than 32k processes.
Fixes: 1be7f75d1668 ("bpf: enable non-root eBPF programs")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index db2574e..89bcaa0 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2049,15 +2049,18 @@
return -E2BIG;
}
- /* remember this map */
- env->used_maps[env->used_map_cnt++] = map;
-
/* hold the map. If the program is rejected by verifier,
* the map will be released by release_maps() or it
* will be used by the valid program until it's unloaded
* and all maps are released in free_bpf_prog_info()
*/
- bpf_map_inc(map, false);
+ map = bpf_map_inc(map, false);
+ if (IS_ERR(map)) {
+ fdput(f);
+ return PTR_ERR(map);
+ }
+ env->used_maps[env->used_map_cnt++] = map;
+
fdput(f);
next_insn:
insn++;