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bpf: Fix leak in LINK_UPDATE and enforce empty old_prog_fd

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Fix bug of not putting bpf_link in LINK_UPDATE command.
Also enforce zeroed old_prog_fd if no BPF_F_REPLACE flag is specified.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200424052045.4002963-1-andriin@fb.com
This commit is contained in:
Andrii Nakryiko 2020-04-23 22:20:44 -07:00 committed by Alexei Starovoitov
parent 5ca1ca01fa
commit 4adb7a4a15
1 changed files with 9 additions and 2 deletions
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11
kernel/bpf/syscall.c
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@ -3628,8 +3628,10 @@ static int link_update(union bpf_attr *attr)
return PTR_ERR(link);
new_prog = bpf_prog_get(attr->link_update.new_prog_fd);
if (IS_ERR(new_prog))
return PTR_ERR(new_prog);
if (IS_ERR(new_prog)) {
ret = PTR_ERR(new_prog);
goto out_put_link;
}
if (flags & BPF_F_REPLACE) {
old_prog = bpf_prog_get(attr->link_update.old_prog_fd);
@ -3638,6 +3640,9 @@ static int link_update(union bpf_attr *attr)
old_prog = NULL;
goto out_put_progs;
}
} else if (attr->link_update.old_prog_fd) {
ret = -EINVAL;
goto out_put_progs;
}
#ifdef CONFIG_CGROUP_BPF
@ -3653,6 +3658,8 @@ out_put_progs:
bpf_prog_put(old_prog);
if (ret)
bpf_prog_put(new_prog);
out_put_link:
bpf_link_put(link);
return ret;
}