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AJvYcCX+8tz+7ICcPCLZ5gB3QieC1pAfq+Ihk4vMwcUPVsBsLmHJvm2eq1BixP/OixMkXoJ7pCRYuSrJe5+rDzg=@vger.kernel.org X-Gm-Message-State: AOJu0YyauA1mHHrpGdRpjzjTYsCT0v7031wlYhgp5lMlj488YK0LBUo/ HVxFGbX4sWKAF1pZ4z0ko7Xzcx4bJZu/ifiblM0iD8HB8uExUH4wTdf2reGnwcGp1Xy/I1BlXA= = X-Google-Smtp-Source: AGHT+IHJvRe9BLo2HN0m+AxXH/BvYMMn7BIpiifD1eWAlC2PY4kjjioOtPMWBI6grulhDzsPYO6sUfue7w== X-Received: from jrife-kvm.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:63c1]) (user=jrife job=sendgmr) by 2002:a17:90a:c90d:b0:2e2:a810:c3e4 with SMTP id 98e67ed59e1d1-2e77e90a214mr13074a91.4.1729883342024; Fri, 25 Oct 2024 12:09:02 -0700 (PDT) Date: Fri, 25 Oct 2024 19:08:54 +0000 In-Reply-To: <20241025182149.500274-1-mathieu.desnoyers@efficios.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241025182149.500274-1-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.47.0.163.g1226f6d8fa-goog Message-ID: <20241025190854.3030636-1-jrife@google.com> Subject: Re: [RFC PATCH v1] tracing: Fix syscall tracepoint use-after-free From: Jordan Rife To: mathieu.desnoyers@efficios.com Cc: acme@kernel.org, alexander.shishkin@linux.intel.com, andrii.nakryiko@gmail.com, ast@kernel.org, bpf@vger.kernel.org, joel@joelfernandes.org, jrife@google.com, linux-kernel@vger.kernel.org, mark.rutland@arm.com, mhiramat@kernel.org, mingo@redhat.com, mjeanson@efficios.com, namhyung@kernel.org, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, syzbot+b390c8062d8387b6272a@syzkaller.appspotmail.com, yhs@fb.com Content-Type: text/plain; charset="UTF-8" > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index 59de664e580d..1191dc1d4206 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -3006,14 +3006,21 @@ static void bpf_link_free(struct bpf_link *link) > bpf_prog_put(link->prog); I think we would need the same treatment with bpf_prog_put here. Something like, tracepoint_call_rcu(raw_tp->btp->tp, &link->prog->aux->rcu, bpf_link_defer_bpf_prog_put); static void bpf_link_defer_bpf_prog_put(struct rcu_head *rcu) { struct bpf_prog_aux *aux = container_of(rcu, struct bpf_prog_aux, rcu); bpf_prog_put(aux->prox); } Alternatively, some context would need to be passed down to __bpf_prog_put_noref via the call to bpf_prog_put so it can choose whether or not to use call_rcu or call_rcu_tasks_trace. > -static inline void release_probes(struct tracepoint_func *old) > +static bool tracepoint_is_syscall(struct tracepoint *tp) > +{ > + return !strcmp(tp->name, "sys_enter") || !strcmp(tp->name, "sys_exit"); > +} I'm curious if it might be better to add some field to struct tracepoint like "sleepable" rather than adding a special case here based on the name? Of course, if it's only ever going to be these two cases then maybe adding a new field doesn't make sense. -Jordan