Messages in this thread | | | Date | Mon, 8 Apr 2024 17:10:48 -0700 | Subject | Re: [PATCH] bpf: dereference of null in __cgroup_bpf_query() function | From | Martin KaFai Lau <> |
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On 4/6/24 8:14 AM, Mikhail Lobanov wrote: > In the __cgroup_bpf_query() function, it is possible to dereference > the null pointer in the line id = prog->aux->id; since there is no > check for a non-zero value of the variable prog. > > Found by Linux Verification Center (linuxtesting.org) with SVACE. > > Fixes: af6eea57437a ("bpf: Implement bpf_link-based cgroup BPF program attachment") > Cc: stable@vger.kernel.org > Signed-off-by: Mikhail Lobanov <m.lobanov@rosalinux.ru> > --- > kernel/bpf/cgroup.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c > index 491d20038cbe..7f2db96f0c6a 100644 > --- a/kernel/bpf/cgroup.c > +++ b/kernel/bpf/cgroup.c > @@ -1092,6 +1092,8 @@ static int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr, > i = 0; > hlist_for_each_entry(pl, progs, node) { > prog = prog_list_prog(pl); > + if (!prog_list_prog(pl))
prog cannot be null. It is under cgroup_lock().
> + continue; > id = prog->aux->id; > if (copy_to_user(prog_ids + i, &id, sizeof(id))) > return -EFAULT;
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