From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C68A3A9624; Mon, 20 Jul 2026 08:54:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784537688; cv=none; b=KxxWnmnLxXsEreH/Cqc7TNGl4qXqyy31qHdB1vcBUrYvraRpKJ4D9QE1tJte+qig1gqf5yAL/MEQuNuS9P8dWGPNPsVi5ftkmkUBjO6D3vx7/bqu3Pj5hSNZiz5ThRPQV7LlkKIat9Gbtf3x2KVuvvgIJh0M4p5c+wJbbL6yaUE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784537688; c=relaxed/simple; bh=ER4h41nxh8wOjXQ1MeCGfCWy8bVkDsfbe9Wje8dQ3sA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lOJPxHE742XZQUS+35xYtQiIL33IXZYc9nRFOm/JnQv4suKYMtviBPT9UrExK9gXh+WWkpNP8Ke8eL7UDVQ6w53KkWZ78Q+LgBcSoNC4Tvbbs5NPMs6a4r+69XWeMQG0i5dvjA7UGK+WKnVNG+mXnUqEev1g3GtOHeLHtfKPXkU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HhDzV2UF; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HhDzV2UF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F9321F000E9; Mon, 20 Jul 2026 08:54:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784537686; bh=fup5XMJ6sgb5lXCta8odLe0ofoInKtEBXBWu3QUMy3A=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=HhDzV2UFaZ+VCm5IHOFQVbwGmrbdqIHhvxQJVBgqxFBa1RUCcltaUdELdpl2+d9oL oiR4YELsB2kfQU+4VSXn2vfODPSPTZ4ZZGYRw7NRaNWMWAXtdsEOsNuCoD0e67WPcY CuvU7TS2VPrVu4HCnFrke7/e/u0OijUka+zM9cnH3nGc64SNmrLAodsfteh5kTN2xo LjfnzuCGCoPmfJ+mmZ+1vqKXIjXBQomDk4K9Wfd7JR7dzDP13btP1iX1Eeuo4rtBSL TVlAzfQtKQK9kXxhbnPL2ivh2EgztodCse6ouRTvNB0P6RVEgzm/ZWFRfR5crFQ7Tc 2Vt7G9Cf4bptw== From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: stable@vger.kernel.org, Tao Chen , bpf@vger.kernel.org, Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , Quentin Monnet , STAR Labs SG Subject: [PATCH bpf-next 5/9] bpf: Disable preemption in bpf_get_stackid Date: Mon, 20 Jul 2026 10:53:47 +0200 Message-ID: <20260720085351.655075-6-jolsa@kernel.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260720085351.655075-1-jolsa@kernel.org> References: <20260720085351.655075-1-jolsa@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The get_perf_callchain call needs disabled preemption plus we need it disabled as long as we access its returned trace entries buffer. Note the bpf_get_stackid_pe function is executed already with preemption disabled. Cc: stable@vger.kernel.org Fixes: d5a3b1f69186 ("bpf: introduce BPF_MAP_TYPE_STACK_TRACE") Reported-by: Tao Chen Closes: https://lore.kernel.org/bpf/20260206090653.1336687-2-chen.dylane@linux.dev/ Signed-off-by: Jiri Olsa --- kernel/bpf/stackmap.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 83efd5892d90..a64b14ffd1e8 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -625,30 +625,37 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, struct perf_callchain_entry *trace; struct stackid stackid; bool kernel = !user; + int err = -EFAULT; u32 max_depth; - int err; if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) return -EINVAL; max_depth = stack_map_calculate_max_depth(map->value_size, elem_size, flags); + + preempt_disable(); trace = get_perf_callchain(regs, kernel, user, max_depth, false, false, 0); if (unlikely(!trace)) /* couldn't fetch the stack trace */ - return -EFAULT; + goto out; err = stackid_fastpath(&stackid, map, trace, flags); if (err != -ENOENT) - return err; + goto out; new_bucket = stackid_new_bucket(&stackid, map, trace, flags); - if (!new_bucket) - return -ENOMEM; + if (new_bucket) { + preempt_enable(); + return stackid_install(&stackid, map, new_bucket, flags); + } + err = -ENOMEM; - return stackid_install(&stackid, map, new_bucket, flags); +out: + preempt_enable(); + return err; } const struct bpf_func_proto bpf_get_stackid_proto = { -- 2.54.0