From: Daniel Xu Date: Wed, 28 Jul 2021 23:09:21 +0000 (-0700) Subject: libbpf: Do not close un-owned FD 0 on errors X-Git-Tag: v5.14-rc6~21^2~38^2~2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c34c338a40e4f3b6f80889cd17fd9281784d1c32;p=thirdparty%2Fkernel%2Flinux.git libbpf: Do not close un-owned FD 0 on errors Before this patch, btf_new() was liable to close an arbitrary FD 0 if BTF parsing failed. This was because: * btf->fd was initialized to 0 through the calloc() * btf__free() (in the `done` label) closed any FDs >= 0 * btf->fd is left at 0 if parsing fails This issue was discovered on a system using libbpf v0.3 (without BTF_KIND_FLOAT support) but with a kernel that had BTF_KIND_FLOAT types in BTF. Thus, parsing fails. While this patch technically doesn't fix any issues b/c upstream libbpf has BTF_KIND_FLOAT support, it'll help prevent issues in the future if more BTF types are added. It also allow the fix to be backported to older libbpf's. Fixes: 3289959b97ca ("libbpf: Support BTF loading and raw data output in both endianness") Signed-off-by: Daniel Xu Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/5969bb991adedb03c6ae93e051fd2a00d293cf25.1627513670.git.dxu@dxuuu.xyz --- diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index b46760b93bb40..7ff3d5ce44f99 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -804,6 +804,7 @@ static struct btf *btf_new(const void *data, __u32 size, struct btf *base_btf) btf->nr_types = 0; btf->start_id = 1; btf->start_str_off = 0; + btf->fd = -1; if (base_btf) { btf->base_btf = base_btf; @@ -832,8 +833,6 @@ static struct btf *btf_new(const void *data, __u32 size, struct btf *base_btf) if (err) goto done; - btf->fd = -1; - done: if (err) { btf__free(btf);