From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 AAA741D68D for ; Wed, 4 Oct 2023 18:13:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2BBE2C433C7; Wed, 4 Oct 2023 18:13:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1696443188; bh=18UjO8LbYMW0+VTYOUVXoBZuAr2OYTRXrB/JfMP1+DA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Dm0TQkfyZzqecbOwgcOx8LrblCKZFN+cXqTbRoG9RhHIygd5dXHudj8zy08cmeoIj /ncUnDRSC2nWhUOs4zJpWdgYJUb0UzefFyoYVpRRc/E8k82SZwYbAlRN786GH/uu+X bmTz6PvWEvTwLCzd8sMYYcPfQLqKdQGlfN+MgHlk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Hsin-Wei Hung , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.1 039/259] bpf: Avoid deadlock when using queue and stack maps from NMI Date: Wed, 4 Oct 2023 19:53:32 +0200 Message-ID: <20231004175219.237470493@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231004175217.404851126@linuxfoundation.org> References: <20231004175217.404851126@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Toke Høiland-Jørgensen [ Upstream commit a34a9f1a19afe9c60ca0ea61dfeee63a1c2baac8 ] Sysbot discovered that the queue and stack maps can deadlock if they are being used from a BPF program that can be called from NMI context (such as one that is attached to a perf HW counter event). To fix this, add an in_nmi() check and use raw_spin_trylock() in NMI context, erroring out if grabbing the lock fails. Fixes: f1a2e44a3aec ("bpf: add queue and stack maps") Reported-by: Hsin-Wei Hung Tested-by: Hsin-Wei Hung Co-developed-by: Hsin-Wei Hung Signed-off-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/20230911132815.717240-1-toke@redhat.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/queue_stack_maps.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/queue_stack_maps.c b/kernel/bpf/queue_stack_maps.c index 8a5e060de63bc..a8fe640318c6c 100644 --- a/kernel/bpf/queue_stack_maps.c +++ b/kernel/bpf/queue_stack_maps.c @@ -102,7 +102,12 @@ static int __queue_map_get(struct bpf_map *map, void *value, bool delete) int err = 0; void *ptr; - raw_spin_lock_irqsave(&qs->lock, flags); + if (in_nmi()) { + if (!raw_spin_trylock_irqsave(&qs->lock, flags)) + return -EBUSY; + } else { + raw_spin_lock_irqsave(&qs->lock, flags); + } if (queue_stack_map_is_empty(qs)) { memset(value, 0, qs->map.value_size); @@ -132,7 +137,12 @@ static int __stack_map_get(struct bpf_map *map, void *value, bool delete) void *ptr; u32 index; - raw_spin_lock_irqsave(&qs->lock, flags); + if (in_nmi()) { + if (!raw_spin_trylock_irqsave(&qs->lock, flags)) + return -EBUSY; + } else { + raw_spin_lock_irqsave(&qs->lock, flags); + } if (queue_stack_map_is_empty(qs)) { memset(value, 0, qs->map.value_size); @@ -197,7 +207,12 @@ static int queue_stack_map_push_elem(struct bpf_map *map, void *value, if (flags & BPF_NOEXIST || flags > BPF_EXIST) return -EINVAL; - raw_spin_lock_irqsave(&qs->lock, irq_flags); + if (in_nmi()) { + if (!raw_spin_trylock_irqsave(&qs->lock, irq_flags)) + return -EBUSY; + } else { + raw_spin_lock_irqsave(&qs->lock, irq_flags); + } if (queue_stack_map_is_full(qs)) { if (!replace) { -- 2.40.1