The following commit has been merged into the perf/core branch of tip:

Commit-ID: 5fe6e308abaea082c20fbf2aa5df8e14495622cf Gitweb: https://git.kernel.org/tip/5fe6e308abaea082c20fbf2aa5df8e14495622cf Author: Oleg Nesterov oleg@redhat.com AuthorDate: Tue, 13 Aug 2024 17:25:24 +02:00 Committer: Peter Zijlstra peterz@infradead.org CommitterDate: Thu, 05 Sep 2024 16:56:13 +02:00

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: 89ae89f53d20 ("bpf: Add multi uprobe link") Closes: https://lore.kernel.org/all/000000000000382d39061f59f2dd@google.com/ Reported-by: syzbot+f7a1c2c2711e4a780f19@syzkaller.appspotmail.com Signed-off-by: Oleg Nesterov oleg@redhat.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Acked-by: Andrii Nakryiko andrii@kernel.org Acked-by: Jiri Olsa jolsa@kernel.org Tested-by: syzbot+f7a1c2c2711e4a780f19@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240813152524.GA7292@redhat.com --- kernel/trace/bpf_trace.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 4e391da..90cd30e 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -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);