From: Daniel Xu dxu@dxuuu.xyz
[ Upstream commit c34c338a40e4f3b6f80889cd17fd9281784d1c32 ]
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 dxu@dxuuu.xyz Signed-off-by: Andrii Nakryiko andrii@kernel.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Yonghong Song yhs@fb.com Link: https://lore.kernel.org/bpf/5969bb991adedb03c6ae93e051fd2a00d293cf25.1627513... Signed-off-by: Sasha Levin sashal@kernel.org --- tools/lib/bpf/btf.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index d57e13a13798..1d9e5b35524c 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -805,6 +805,7 @@ 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; @@ -833,8 +834,6 @@ 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);