]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
bpf: hash map, avoid deadlock with suitable hash mask
authorTonghao Zhang <tong@infragraf.org>
Wed, 11 Jan 2023 09:29:01 +0000 (17:29 +0800)
committerMartin KaFai Lau <martin.lau@kernel.org>
Fri, 13 Jan 2023 02:55:42 +0000 (18:55 -0800)
commit9f907439dc80e4a2fcfb949927b36c036468dbb3
tree7e06977ae0a62da945925ec8b49a579864fdeb54
parente7895f017b79410bf4591396a733b876dc1e0e9d
bpf: hash map, avoid deadlock with suitable hash mask

The deadlock still may occur while accessed in NMI and non-NMI
context. Because in NMI, we still may access the same bucket but with
different map_locked index.

For example, on the same CPU, .max_entries = 2, we update the hash map,
with key = 4, while running bpf prog in NMI nmi_handle(), to update
hash map with key = 20, so it will have the same bucket index but have
different map_locked index.

To fix this issue, using min mask to hash again.

Fixes: 20b6cc34ea74 ("bpf: Avoid hashtab deadlock with map_locked")
Signed-off-by: Tonghao Zhang <tong@infragraf.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Song Liu <song@kernel.org>
Cc: Yonghong Song <yhs@fb.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230111092903.92389-1-tong@infragraf.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
kernel/bpf/hashtab.c