On 10/31/21 10:13 AM, Eric Dumazet wrote:
From: Eric Dumazet <edumazet@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Joanne Koong <joannekoong@xxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
LGTM with a suggestion below.
Acked-by: Yonghong Song <yhs@xxxxxx>
---
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,
There is a pending patch
https://lore.kernel.org/bpf/20211029224909.1721024-2-joannekoong@xxxxxx/T/#u
to rename say lookup_elem to bloom_map_lookup_elem.
I think we should change
this delete_elem to bloom_map_delete_elem as well.
.map_check_btf = check_btf,
.map_btf_name = "bpf_bloom_filter",
.map_btf_id = &bpf_bloom_btf_id,
