Commit 5fe6e308 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Peter Zijlstra
Browse files

bpf: Fix use-after-free in bpf_uprobe_multi_link_attach() 

If bpf_link_prime() fails, bpf_uprobe_multi_link_attach() goes to the
error_free label and frees the array of bpf_uprobe's without calling
bpf_uprobe_unregister().

This leaks bpf_uprobe->uprobe and worse, this frees bpf_uprobe->consumer
without removing it from the uprobe->consumers list.

Fixes: 89ae89f5 ("bpf: Add multi uprobe link")
Closes: https://lore.kernel.org/all/000000000000382d39061f59f2dd@google.com/


Reported-by: default avatar <syzbot+f7a1c2c2711e4a780f19@syzkaller.appspotmail.com>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Tested-by: default avatar <syzbot+f7a1c2c2711e4a780f19@syzkaller.appspotmail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240813152524.GA7292@redhat.com
parent 62c0b106

kernel/trace/bpf_trace.c

+6 −3
Original line number Diff line number Diff line
@@ -3484,17 +3484,20 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr 
						    &uprobes[i].consumer);

		if (IS_ERR(uprobes[i].uprobe)) {

			err = PTR_ERR(uprobes[i].uprobe);

			bpf_uprobe_unregister(uprobes, i);

			goto error_free;

			link->cnt = i;

			goto error_unregister;

		}

	}



	err = bpf_link_prime(&link->link, &link_primer);

	if (err)

		goto error_free;

		goto error_unregister;



	return bpf_link_settle(&link_primer);



error_unregister:

	bpf_uprobe_unregister(uprobes, link->cnt);



error_free:

	kvfree(uprobes);

	kfree(link);