netdev - [PATCH bpf-next] bpf: add missing map_delete

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Message-Id: <20211031171353.4092388-1-eric.dumazet@gmail.com>
Date:   Sun, 31 Oct 2021 10:13:53 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Cc:     "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        bpf <bpf@...r.kernel.org>, Joanne Koong <joannekoong@...com>,
        Andrii Nakryiko <andrii@...nel.org>,
        syzbot <syzkaller@...glegroups.com>
Subject: [PATCH bpf-next] bpf: add missing map_delete_elem method to bloom filter map

From: Eric Dumazet <edumazet@...gle.com>

Without it, kernel crashes in map_delete_elem(), as reported
by syzbot.

BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD 72c97067 P4D 72c97067 PUD 1e20c067 PMD 0
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 6518 Comm: syz-executor196 Not tainted 5.15.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc90002bafcb8 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 1ffff92000575f9f RCX: 0000000000000000
RDX: 1ffffffff1327aba RSI: 0000000000000000 RDI: ffff888025a30c00
RBP: ffffc90002baff08 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff818525d8 R11: 0000000000000000 R12: ffffffff8993d560
R13: ffff888025a30c00 R14: ffff888024bc0000 R15: 0000000000000000
FS:  0000555557491300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000070189000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 map_delete_elem kernel/bpf/syscall.c:1220 [inline]
 __sys_bpf+0x34f1/0x5ee0 kernel/bpf/syscall.c:4606
 __do_sys_bpf kernel/bpf/syscall.c:4719 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4717 [inline]
 __x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4717
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]

Fixes: 9330986c0300 ("bpf: Add bloom filter map implementation")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Joanne Koong <joannekoong@...com>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Andrii Nakryiko <andrii@...nel.org>
Reported-by: syzbot <syzkaller@...glegroups.com>
---
 kernel/bpf/bloom_filter.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/bpf/bloom_filter.c b/kernel/bpf/bloom_filter.c
index 7c50232b7571f3f038dd45b5c0bd7289125e6d43..31a7af15a83d74af1d88d04cc8d71aa7d403b4ef 100644
--- a/kernel/bpf/bloom_filter.c
+++ b/kernel/bpf/bloom_filter.c
@@ -77,6 +77,11 @@ static int pop_elem(struct bpf_map *map, void *value)
 	return -EOPNOTSUPP;
 }
 
+static int delete_elem(struct bpf_map *map, void *value)
+{
+	return -EOPNOTSUPP;
+}
+
 static struct bpf_map *map_alloc(union bpf_attr *attr)
 {
 	u32 bitset_bytes, bitset_mask, nr_hash_funcs, nr_bits;
@@ -189,6 +194,7 @@ const struct bpf_map_ops bloom_filter_map_ops = {
 	.map_pop_elem = pop_elem,
 	.map_lookup_elem = lookup_elem,
 	.map_update_elem = update_elem,
+	.map_delete_elem = delete_elem,
 	.map_check_btf = check_btf,
 	.map_btf_name = "bpf_bloom_filter",
 	.map_btf_id = &bpf_bloom_btf_id,
-- 
2.33.1.1089.g2158813163f-goog