From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f181.google.com (mail-pl1-f181.google.com [209.85.214.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B0EE93911A8 for ; Tue, 16 Jun 2026 22:26:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.181 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781648818; cv=none; b=qpxlxTOg/sM6Gsy7ekdY79EpkODavTcTIol/MbmTpRxZRjBYKI1marDOFp6NtQenyW/SN9Wow6GWxHxr2UI1QCcrjerm0g9Qf7buMMnj5Lur5pexfOVUVF4X2h3dDRmJhFzG6D+YajqiIhImK7IMwetfRzlh7pPZ6B1CPdx92kk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781648818; c=relaxed/simple; bh=lagiunzXSq9oC2yFzwByQw8wxuRhAtHQcjGd/oG0Ld0=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=HX19aS8VjYiPvnkQPKBArfNzPgu7PqlYf/hXQAa2fjpy5nOCo8jtstfqT0i7sUCGrYUWTNI/AoW4WbWfn810beMDsN9WZC9Ryc98w20K6xdRufGcvMfF1pKDEx2+/tvqM0zl42wbT8uQKCm9Hc5Np5YqmFQdKx5CqfdJenSD6/Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=HNGO6CoV; arc=none smtp.client-ip=209.85.214.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="HNGO6CoV" Received: by mail-pl1-f181.google.com with SMTP id d9443c01a7336-2c0b944f6edso51949525ad.2 for ; Tue, 16 Jun 2026 15:26:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1781648816; x=1782253616; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=b4Yll/Wvi91nYOEpP83UIdJkAu2UP4DX4txS/t/t0Jo=; b=HNGO6CoVvU+jpqeojl4yXlU6oILeWdTWJOTnQeAiWLFfpE/0lm4sMIiEb/UPgeQhz7 xvAyzgDD8VO49AyhpumkoKUGQjs4xnhy/UDoStbEo9lbrzujhClk53lKaprjv1BldOky aeriE+VFInLcOBUOb+mAW8HHk3mw9e0MD3Mje9fnX/CBZGOaWUW0eT/HbmtquwY1F4L9 7pQRpIV8l7ikNn4pLPSupU/Ww5RO0Tp2eaAJZu1E5nVYQjvsquSMcL1zmIzWMaUN+40K By6E5RuK4uPFFWJm/XY14uGBoqPWvT0WfXPNPcKyPHVtEQuVXumXOAfKXwpyU5/mhWt5 85Vg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781648816; x=1782253616; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=b4Yll/Wvi91nYOEpP83UIdJkAu2UP4DX4txS/t/t0Jo=; b=eQEBWUMYes+GOZdxiufem194Fqmv7TFSDFt84mHbSy5aNqfDpU+Bz1DuVjVP1890CR rTsx16p80MhQ7wF33toBX6rSQOgCyR6lEzdsAK6EifNAp1Pio3ygmb0Qajecd1ZIQckk MnD6Nv2SYbxZx88QeYyTsSvLuJPUoTB03QyGwOERB5vpwYda2Cvuu217sO5ADkwS/CMM tC2MndNGUOGr4oVU1P4BewYExHu9aMYKmqFZYWYDA51lSQTzSqkhqTIHnH9Bbi3s5fHw QFbtnhCVO3qZsSuLzrMpauDMkf3cSJeZnrHfyIAMPYiN8QDMmSgJvIJ4eqpnpHoVAihD 50Yw== X-Forwarded-Encrypted: i=1; AFNElJ95Ev7dATJN2schnQkET3QtdEjiwlTubHRv3Twg0BLo9WUK03ThAVUs37Cu96tl7leFmBG8UF2BX1BzgWM=@vger.kernel.org X-Gm-Message-State: AOJu0YzH0FA96z5+4m4Tl2g6F5F1hzYr8D/Kl67q77Kn9TH+Rf5VOLJC QN/d6BdVDzUwqJPwY92FOnqcV8HJXlMK+GTqojBO668cp/RksB5s5XGq X-Gm-Gg: Acq92OGPZ7DFQuGJBXDWwZ7+i6oapbjALciS12kwK6hGaxQTSTOpDosQBiink/gBVvv vspNZsh7pIjg1jRF6+Fquh8k7cCjIMTCoVyRuJlDG76mGJJ4Hf0dK6VsclcHtE4i3zc3C2iJZ2b ZqLMqa3v+t3fG1zcHo1g6HH9mncwUzluVEmEdl8RcrStBW1TjfTqvqkvrcoZoa1cthHCsGQ5g/J yyEFaHeLDsAUu4F3AM75rRfkinV09YbVjWgvDKlMB233KmgHMJKOnSMezMY7r+5erLFQWYGvK1G pnU2VEClEsj4kzFTQC1w7BCQ/ZE3k6gdzl1OL079+fBVJHaioG/WgnkIgOWRW+MuMYct8Ruo+Jx 9xQLrWhzzwPFMGGKBSl8Z1fTdIiH427uYHMkeeRMZtXrhsyY236hU32d48KUx4+ZoDJxFitl674 INJKbH6lbtM+ykVLlgAMaDl93yErP1tiRy9ZntxnYeflmFHsrMO0oO8t8EWGVEVi1eZfU3/bGJt WqE X-Received: by 2002:a17:902:f606:b0:2c0:b932:8680 with SMTP id d9443c01a7336-2c6bc0b76camr10361585ad.10.1781648815957; Tue, 16 Jun 2026 15:26:55 -0700 (PDT) Received: from moksh-Nitro-ANV15-51.. ([203.192.239.31]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2c6a758a3c6sm22532005ad.52.2026.06.16.15.26.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Jun 2026 15:26:55 -0700 (PDT) From: Moksh Panicker To: kuba@kernel.org Cc: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, Moksh Panicker , syzbot+1cf303af03cf30b1275a@syzkaller.appspot.com Subject: [PATCH] netdevsim: Fix deadlock in del_device_store() and nsim_bus_exit() Date: Tue, 16 Jun 2026 22:26:44 +0000 Message-Id: <20260616222644.41344-1-mokshpanicker.7@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit del_device_store() and nsim_bus_exit() both hold nsim_bus_dev_list_lock while calling nsim_bus_dev_del(), which calls device_unregister() which internally acquires the device lock. If another thread already holds the device lock and tries to acquire nsim_bus_dev_list_lock, a deadlock occurs: INFO: task hung in nsim_bus_dev_del Fix this by releasing nsim_bus_dev_list_lock before calling nsim_bus_dev_del() in both locations, after the devices have already been removed from the list with list_del(). Reported-by: syzbot+1cf303af03cf30b1275a@syzkaller.appspot.com Closes: https://syzkaller.appspot.com/bug?extid=1cf303af03cf30b1275a Signed-off-by: Moksh Panicker --- drivers/net/netdevsim/bus.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/net/netdevsim/bus.c b/drivers/net/netdevsim/bus.c index 41483e371..0f02ff8ad 100644 --- a/drivers/net/netdevsim/bus.c +++ b/drivers/net/netdevsim/bus.c @@ -241,11 +241,12 @@ del_device_store(const struct bus_type *bus, const char *buf, size_t count) if (nsim_bus_dev->dev.id != id) continue; list_del(&nsim_bus_dev->list); - nsim_bus_dev_del(nsim_bus_dev); err = 0; break; } mutex_unlock(&nsim_bus_dev_list_lock); + if (!err) + nsim_bus_dev_del(nsim_bus_dev); return !err ? count : err; } static BUS_ATTR_WO(del_device); @@ -527,11 +528,11 @@ void nsim_bus_exit(void) complete(&nsim_bus_devs_released); mutex_lock(&nsim_bus_dev_list_lock); - list_for_each_entry_safe(nsim_bus_dev, tmp, &nsim_bus_dev_list, list) { + list_for_each_entry_safe(nsim_bus_dev, tmp, &nsim_bus_dev_list, list) list_del(&nsim_bus_dev->list); - nsim_bus_dev_del(nsim_bus_dev); - } mutex_unlock(&nsim_bus_dev_list_lock); + list_for_each_entry_safe(nsim_bus_dev, tmp, &nsim_bus_dev_list, list) + nsim_bus_dev_del(nsim_bus_dev); wait_for_completion(&nsim_bus_devs_released); -- 2.34.1