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net, sockmap: Don't call bpf_prog_put() on NULL pointer 

If bpf_prog_inc_not_zero() fails for skb_parser, then bpf_prog_put() is
called unconditionally on skb_verdict, even though it may be NULL. Fix
and tidy up error path.

Fixes: 743df8b774 ("bpf, sockmap: Check skb_verdict and skb_parser programs explicitly")
Addresses-Coverity-ID: 1497799: Null pointer dereferences (FORWARD_NULL)
Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20201012170952.60750-1-alex.dewar90@gmail.com
pull/193/head
Alex Dewar 2020-10-12 18:09:53 +01:00 committed by Daniel Borkmann
parent 8a3feed90e
commit 83c11c1755
1 changed files with 9 additions and 7 deletions
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16
net/core/sock_map.c
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@ -238,17 +238,18 @@ static int sock_map_link(struct bpf_map *map, struct sk_psock_progs *progs,
int ret;
skb_verdict = READ_ONCE(progs->skb_verdict);
skb_parser = READ_ONCE(progs->skb_parser);
if (skb_verdict) {
skb_verdict = bpf_prog_inc_not_zero(skb_verdict);
if (IS_ERR(skb_verdict))
return PTR_ERR(skb_verdict);
}
skb_parser = READ_ONCE(progs->skb_parser);
if (skb_parser) {
skb_parser = bpf_prog_inc_not_zero(skb_parser);
if (IS_ERR(skb_parser)) {
bpf_prog_put(skb_verdict);
return PTR_ERR(skb_parser);
ret = PTR_ERR(skb_parser);
goto out_put_skb_verdict;
}
}
@ -257,7 +258,7 @@ static int sock_map_link(struct bpf_map *map, struct sk_psock_progs *progs,
msg_parser = bpf_prog_inc_not_zero(msg_parser);
if (IS_ERR(msg_parser)) {
ret = PTR_ERR(msg_parser);
goto out;
goto out_put_skb_parser;
}
}
@ -311,11 +312,12 @@ out_drop:
out_progs:
if (msg_parser)
bpf_prog_put(msg_parser);
out:
if (skb_verdict)
bpf_prog_put(skb_verdict);
out_put_skb_parser:
if (skb_parser)
bpf_prog_put(skb_parser);
out_put_skb_verdict:
if (skb_verdict)
bpf_prog_put(skb_verdict);
return ret;
}