]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
libbpf: Do not close un-owned FD 0 on errors
authorDaniel Xu <dxu@dxuuu.xyz>
Wed, 28 Jul 2021 23:09:21 +0000 (16:09 -0700)
committerDaniel Borkmann <daniel@iogearbox.net>
Fri, 6 Aug 2021 23:39:15 +0000 (01:39 +0200)
commitc34c338a40e4f3b6f80889cd17fd9281784d1c32
tree332be058a454d94d772a7213578003e1b07cf776
parent78d14bda861dd2729f15bb438fe355b48514bfe0
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 <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/5969bb991adedb03c6ae93e051fd2a00d293cf25.1627513670.git.dxu@dxuuu.xyz
tools/lib/bpf/btf.c