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received-spf: None (protection.outlook.com: fb.com does not designate permitted sender hosts) x-microsoft-antispam-message-info: ILIRv1xtzgjDoyGbIuQdFSDeVPkj/Vux5N365a3Zx9fc9SBMFfbxVjmIj4uR1i3tPOVMmbyB7e/EZEFuq/6REQ/Z6pzyTjMazx5NxXYmqEvafEZ87Ovu+FQs+7D3tMlXRVEjvYCm7ZaMDkT3jv8xauig+sg8sV8nyqbjSasajuPN6bfyBzg7HqDgkhuFo0ucWPyn9+DlTBJaAZncIZ5J5yxNb3nS67ELl5hqOTqlK9T2ftvS8qR70JDqKQIUXH4Bn+BFaTbilv7eW2be5FKeT2tQtWf+5CItyB+NbZY72UIACsLQwvPkHv4WXKYL41Z4VT916aSMezyn3ddx5pyAb0znMKqSbjbTjdCHAj4ZIvM= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: ec095717-94c7-4db7-5f03-08d63834b541 X-MS-Exchange-CrossTenant-originalarrivaltime: 22 Oct 2018 15:40:35.8456 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR15MB1744 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-10-22_11:,, signatures=0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 19, 2018 at 05:29:51PM -0500, Wenwen Wang wrote: > In btf_parse(), the header of the user-space btf data 'btf_data' is first= ly > parsed and verified through btf_parse_hdr(). In btf_parse_hdr(), the head= er > is copied from user-space 'btf_data' to kernel-space 'btf->hdr' and then > verified. If no error happens during the verification process, the whole > data of 'btf_data', including the header, is then copied to 'data' in > btf_parse(). It is obvious that the header is copied twice here. More > importantly, no check is enforced after the second copy to make sure the > headers obtained in these two copies are same. Given that 'btf_data' > resides in the user space, a malicious user can race to modify the header > between these two copies. By doing so, the user can inject inconsistent > data, which can cause undefined behavior of the kernel and introduce > potential security risk. >=20 > To avoid the above issue, this patch rewrites the header after the second > copy, using 'btf->hdr', which is obtained in the first copy. Acked-by: Martin KaFai Lau