From: Yonghong Song yhs@fb.com
[ Upstream commit 17d8beda277a36203585943e70c7909b60775fd5 ]
Commit 15d83c4d7cef ("bpf: Allow loading of a bpf_iter program") cached btf_id in struct bpf_iter_target_info so later on if it can be checked cheaply compared to checking registered names.
syzbot found a bug that uninitialized value may occur to bpf_iter_target_info->btf_id. This is because we allocated bpf_iter_target_info structure with kmalloc and never initialized field btf_id afterwards. This uninitialized btf_id is typically compared to a u32 bpf program func proto btf_id, and the chance of being equal is extremely slim.
This patch fixed the issue by using kzalloc which will also prevent future likely instances due to adding new fields.
Fixes: 15d83c4d7cef ("bpf: Allow loading of a bpf_iter program") Reported-by: syzbot+580f4f2a272e452d55cb@syzkaller.appspotmail.com Signed-off-by: Yonghong Song yhs@fb.com Signed-off-by: Alexei Starovoitov ast@kernel.org Link: https://lore.kernel.org/bpf/20210212005926.2875002-1-yhs@fb.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/bpf_iter.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c index 8f10e30ea0b08..e8957e911de31 100644 --- a/kernel/bpf/bpf_iter.c +++ b/kernel/bpf/bpf_iter.c @@ -273,7 +273,7 @@ int bpf_iter_reg_target(const struct bpf_iter_reg *reg_info) { struct bpf_iter_target_info *tinfo;
- tinfo = kmalloc(sizeof(*tinfo), GFP_KERNEL); + tinfo = kzalloc(sizeof(*tinfo), GFP_KERNEL); if (!tinfo) return -ENOMEM;