From nobody Tue Aug 25 14:34:10 2026 Received: from mail-yw1-f176.google.com (mail-yw1-f176.google.com [209.85.128.176]) (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 06AFF35B63F for ; Fri, 14 Aug 2026 05:26:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.176 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786685187; cv=none; b=lHXTfgPLViFeWuLae9a9N6u1GBdpbvO04O5T8FPI+LaIJhb611lbsVrc5CukO0oI0rke3OhUpuZljlmryFN4f1L1m8MMdh0AdYIxyGhHr54Q2LTOA0tjobAAZwOceKPq5hfxC1/9CMRAw22zsjbE0n5cPt1ManBdvgjVPRGz6Qw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786685187; c=relaxed/simple; bh=pW7D05ISpQgyDNkTLXmrnAUg5iPB5RsD2+wUMaP+KUU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=XYUtH5THQtwfB/I4D+90FsAJmKc9g9CB9gvZZcuDOpa5RiMYuG6ZHNuGqJ57UcBMnPciHAUQTuEFRpnS7SLXGN49Mcsl1qa63pEGKPFKcVb+zyL0EaYpgfYTZFMgYAkBCnuA7MYtghdu+Eh0IjUOpgud3Qtgb2VHKMUYhWoLLyg= 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=ggUogy8C; arc=none smtp.client-ip=209.85.128.176 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="ggUogy8C" Received: by mail-yw1-f176.google.com with SMTP id 00721157ae682-8200b55dc47so9402227b3.3 for ; Thu, 13 Aug 2026 22:26:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1786685185; x=1787289985; 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:content-type; bh=zrUwKSq5HeSG1i2WP2CVyRO5QXQtrMc0uYjdUEKvfyU=; b=ggUogy8C1o837Lz1LPk2lYZRobUGGBFc2ZikuatJa3Z/ZMmdxHugNZ5ALn14PFojfn naOkzikMgqw6o4MmqgRyTsjN8RqQKyTeeId+5U/9zo6KHub2VsfJ0Eh8LFldX56ujh+z cHif2kKsXZAxjR7wJ94QU/JKlE1upJpENQ0wCnc6nj/NyYrrdzWwvwKyW1hzH+sJu3c6 3RhmCrrLJxXpZRWzSvOTNy917cUfSC2IuVNzGhRq8x0lFaKM2xkiVnWMupzcog4dg8+g +fDP0//bW6IELFY1D5SKOrP9oyF2vbOhail2v0VBuSXPa/38pSexBZc4ZieJgrqyoIu/ D5yA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786685185; x=1787289985; 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:content-type; bh=zrUwKSq5HeSG1i2WP2CVyRO5QXQtrMc0uYjdUEKvfyU=; b=mISFpDL8FDrkPjEr8vCd7fSzJjizOHl0pBHpIFfm6bmq1Gg1NKrKAxLMPxiWaRw4XI jAFNImJJ8QLzdw/7gzrESTtsQJP9b9uw7d8Ux+Lwb+MsuT8ufL5hH+IXOH/8LRkX4CIX SdQgAbK/gRnQ/fnBVj5JZo+cM44qYLSv47InhQZkTM/xbmkFig1vXo53gc+Q1esMiW7c +eKQrtLJPg4FKE/N0B+Lj4UlZtDGl8fsYvzGZaZ/OTEEWHPC1kc3aHWFiupMSqm2RwoV c5z1Bty9tJYTCmnqC3gWEGrQpZSXumPb4wtwCKJpQXNtCr8qF2s+qqy8Qi8lSdt7xmlb Ua1w== X-Forwarded-Encrypted: i=1; AHgh+Rr4Yno35LnyiyGXtExxDSAhWnxpptFoRBErKwsGzfZpqSTu5rHU3e4j9Jn5PnxD4RL2SX+ZGJ1NG5x/Ilk=@vger.kernel.org X-Gm-Message-State: AOJu0Yw0ZwnNSJ7jpR2yJW7HMhFs9EsdZr8gVAbozLfhCh0jaPwOv0UQ +Nh+r7khw8BCyiBFrJFAbH/J6/yXO9dj/AJM1sor+QQWi5yp5PdKtXZp X-Gm-Gg: AR+sD10Sp59AOE8mqfLRv05gDhCREGh5NzE0hJs6+X506r1ExhWAfRSO8V39uTLNXwN lgvpgsfF6YbcD8icrVY788BFDumxnES5Lt1D8f3vdJ/ruI3ilfGaCY2ZdPwnkDz0cCBrNTgnq/l uDOyh6Z2NjS+HRRxhy47H0MGqsWTSDZadQxEDzZADUjnz7kN/yg/eTNtRoW5/4tiZDWOuxmXM1/ HIufqu1PJxNskBbVZiDGRrnjeYh9xHwlfSrnaZ3dev4C2PwMxUXV+KsgZc486dCCjiJf/I0xcA/ 0ohbEy6kGJD6c78wMMwBMvS/RBG/ST7bxczRZxdrL1+pGMflAU9tkEyCXFc5ZVMZ9N0rVzJFNqa DYwdHzhQknTKDdSq11bw8p5xiLbC0CloQ4HMZlLJ8Dl1hVXB0GncwthcOTzNrg7zx7ArUwid7Bk Pc0QxQyboCzfa64ExVvX3QQuvMdgYx4uS8WIpzywqfoqIetZA3wML3rE7Ut3qXO50rK3M= X-Received: by 2002:a05:690c:39d:b0:833:968e:c236 with SMTP id 00721157ae682-8370e1b7cb8mr15102727b3.13.1786685184664; Thu, 13 Aug 2026 22:26:24 -0700 (PDT) Received: from mac.lan ([136.55.173.105]) by smtp.gmail.com with ESMTPSA id 00721157ae682-836bbdc0ac1sm8756617b3.12.2026.08.13.22.26.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Aug 2026 22:26:24 -0700 (PDT) From: "Cen Zhang (Microsoft)" To: mchehab@kernel.org, hverkuil@kernel.org Cc: kees@kernel.org, rongqianfeng@vivo.com, axboe@kernel.dk, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, AutonomousCodeSecurity@microsoft.com, tgopinath@linux.microsoft.com, kys@microsoft.com, blbllhy@gmail.com, stable@vger.kernel.org Subject: [PATCH v3] media: dvb-core: add upper bound check in DMX_SET_BUFFER_SIZE ioctl Date: Fri, 14 Aug 2026 01:26:08 -0400 Message-ID: <20260814052608.39361-1-blbllhy@gmail.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" dvb_dvr_set_buffer_size() and dvb_dmxdev_set_buffer_size() pass the user-supplied size argument directly to vmalloc() without any upper bound check. This allows excessive kernel memory allocation via the DMX_SET_BUFFER_SIZE ioctl, which can lead to system-wide OOM conditions. Kernel panic - not syncing: System is deadlocked on memory Call Trace: out_of_memory+0x12fd/0x1370 __alloc_frozen_pages_noprof+0x2620/0x2fa0 __vmalloc_node_range_noprof+0x7fa/0x1490 dvb_dvr_do_ioctl+0x11e/0x260 (drivers/media/dvb-core/dmxdev.c:296) dvb_usercopy+0x15b/0x360 Fix by clamping both functions to 64 MiB for oversized requests. A quick survey of SATPI, DVBlast, dvbv5-zap, minisatip, TVheadend, MythTV, and MuMuDVB found the largest requested buffer to be about 30 MiB. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Fixes: a095be4b030c ("V4L/DVB (7659): dvb-core: Implement DMX_SET_BUFFER_SI= ZE for dvr") Cc: stable@vger.kernel.org Reported-by: AutonomousCodeSecurity@microsoft.com Link: https://lore.kernel.org/all/20260722193719.81157-1-blbllhy@gmail.com/ Signed-off-by: Cen Zhang (Microsoft) --- V3: - Clamp oversized requests to maximum instead of returning -EINVAL. - Clamp before size comparison to avoid redundant reallocation. - Explain the choice of the 64 MiB limit. V2: - Add Cc: stable and Link: tag. drivers/media/dvb-core/dmxdev.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/media/dvb-core/dmxdev.c b/drivers/media/dvb-core/dmxde= v.c index 3c8bc75e4d6c..330255312c85 100644 --- a/drivers/media/dvb-core/dmxdev.c +++ b/drivers/media/dvb-core/dmxdev.c @@ -20,6 +20,9 @@ #include #include =20 +/* 64 MiB upper bound for DVB ring buffer allocations */ +#define DVB_BUFFER_SIZE_MAX (64 * 1024 * 1024) + static int debug; =20 module_param(debug, int, 0644); @@ -288,6 +291,8 @@ static int dvb_dvr_set_buffer_size(struct dmxdev *dmxde= v, =20 dprintk("%s\n", __func__); =20 + if (size > DVB_BUFFER_SIZE_MAX) + size =3D DVB_BUFFER_SIZE_MAX; if (buf->size =3D=3D size) return 0; if (!size) @@ -327,6 +332,8 @@ static int dvb_dmxdev_set_buffer_size(struct dmxdev_fil= ter *dmxdevfilter, void *newmem; void *oldmem; =20 + if (size > DVB_BUFFER_SIZE_MAX) + size =3D DVB_BUFFER_SIZE_MAX; if (buf->size =3D=3D size) return 0; if (!size) --=20 2.52.0