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bpf: Fix an unitialized value in bpf_iter

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Commit 15d83c4d7c ("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: 15d83c4d7c ("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
This commit is contained in:
Yonghong Song
2021-02-11 16:59:26 -08:00
committed by Alexei Starovoitov
parent 90a82b1fa4
commit 17d8beda27
1 changed files with 1 additions and 1 deletions
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2
kernel/bpf/bpf_iter.c
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@@ -287,7 +287,7 @@ 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;