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[76.251.165.188]) by smtp.gmail.com with ESMTPSA id m17-v6sm7400634otk.1.2018.06.18.18.45.29 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 18 Jun 2018 18:45:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=wblhaoia/wIA4S+Lvax8kQx5mbt+4ozrhGYexmgT32I=; b=drUsXowKil3WtXiDyPN0XYfQUwiqrcTDolae2VN47342iGq2BXA56r3+uMQBIwvZw0 JctMUwKDJIFmtHDWPkk+Th+gNWpsXUZWCbIGfWmrCtKJ/2ytnbNxCQ4aNaBpMoFHc4Gh 0BDF55hhpOwjAOrIkQ5fYfIg5T0FX1xzeUdDfJK1MTPqEoOHfvcrbZti2KsHa1MpiSCf X0fVhda4VwM5fElbmw1RWxc2BLAGSRgwmB8dOd/SWw7GGd5Q1LoJaaDHmixOGlt8u5uP iHyBn8wfcP0mMYJozgNwDk/KzwfpGFc7VOVlfqMNsK37W8bVzTqdijIUrGPN0gvyLxiU 3vEQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references; bh=wblhaoia/wIA4S+Lvax8kQx5mbt+4ozrhGYexmgT32I=; b=jP4DamT/yFxIgBEdPsm6iT+AAIhU/AsZdDXzfFt8mBFTN1INfG7uJuIgbCAwQU1i6/ 9aFD/m7fy4wJV0nLaTQqzIiZtkeSt3em+IvuuieHq78ZuVLNI5qlPYNGbybvIiYk7Iwb iQc/LjgFD/9MI46o/VXEdl8Mc04l2hoyPjJ6kiZWBOmK8ihS+u9StEDekgo4+l/eGqNg JF05nhT+5LEV2/8SwbinfJ+o2AJs8dmFPmgI/kc7p9x3CBNeYNxMT+yF7lS9S9WvYIPQ kbdcxZ0bMVrp/Gz7r14gzxhDDgyQ/d4aH9Sq9x68bm7w9RZy6fGnAAXrWBvOKxKlLZTn APtg== X-Gm-Message-State: APt69E1cxDjo5pPIe9SkxZAVakhj2vX/WJmVjfL79EYEXmsKC99yYWuk ONV2fgSOjrNcxAogiObQ3rQZwCpo X-Google-Smtp-Source: ADUXVKIdBpf7lUFP3K0J2vvQVO78btVEbkESQLbblO7A4I5ruZjaaPCgkfTwVTEnmshaKgFD9r2qeg== X-Received: by 2002:aca:f505:: with SMTP id t5-v6mr8658039oih.62.1529372731044; Mon, 18 Jun 2018 18:45:31 -0700 (PDT) From: Michael Roth To: qemu-devel@nongnu.org Date: Mon, 18 Jun 2018 20:42:06 -0500 Message-Id: <20180619014319.28272-41-mdroth@linux.vnet.ibm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180619014319.28272-1-mdroth@linux.vnet.ibm.com> References: <20180619014319.28272-1-mdroth@linux.vnet.ibm.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4003:c06::232 Subject: [Qemu-devel] [PATCH 040/113] multiboot: Reject kernels exceeding the address space X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , qemu-stable@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZohoMail: RDKM_2 RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Kevin Wolf The code path where mh_load_end_addr is non-zero in the Multiboot header checks that mh_load_end_addr >=3D mh_load_addr and so mb_load_size is checked. However, mb_load_size is not checked when calculated from the file size, when mh_load_end_addr is 0. If the kernel binary size is larger than can fit in the address space after load_addr, we ended up with a kernel_size that is smaller than load_size, which means that we read the file into a too small buffer. Add a check to reject kernel files with such Multiboot headers. Signed-off-by: Kevin Wolf Reviewed-by: Jack Schwartz (cherry picked from commit b17a9054a0652a1481be48a6729e972abf02412f) Signed-off-by: Michael Roth --- hw/i386/multiboot.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/hw/i386/multiboot.c b/hw/i386/multiboot.c index d9a0a95a2f..775aa5bfd0 100644 --- a/hw/i386/multiboot.c +++ b/hw/i386/multiboot.c @@ -247,6 +247,10 @@ int load_multiboot(FWCfgState *fw_cfg, } mb_load_size =3D kernel_file_size - mb_kernel_text_offset; } + if (mb_load_size > UINT32_MAX - mh_load_addr) { + error_report("kernel does not fit in address space"); + exit(1); + } if (mh_bss_end_addr) { if (mh_bss_end_addr < (mh_load_addr + mb_load_size)) { error_report("invalid bss_end_addr address"); --=20 2.11.0