From: Daniel Xu <dxu@xxxxxxxxx>
[ 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@xxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: Yonghong Song <yhs@xxxxxx>
Link: https://lore.kernel.org/bpf/5969bb991adedb03c6ae93e051fd2a00d293cf25.1627513670.git.dxu@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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);
--
2.30.2
