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Wed, 18 May 2022 20:05:55 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AB2C1A404D; Wed, 18 May 2022 20:05:51 +0000 (GMT) Received: from vajain21.in.ibm.com (unknown [9.43.77.53]) by d06av23.portsmouth.uk.ibm.com (Postfix) with SMTP; Wed, 18 May 2022 20:05:51 +0000 (GMT) Received: by vajain21.in.ibm.com (sSMTP sendmail emulation); Thu, 19 May 2022 01:35:50 +0530 From: Vaibhav Jain To: linuxppc-dev@lists.ozlabs.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] powerpc: check previous kernel's ima-kexec-buffer against memory bounds Date: Thu, 19 May 2022 01:35:47 +0530 Message-Id: <20220518200547.655788-1-vaibhav@linux.ibm.com> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: biRZhQYwiHimDKKLP5rnfJK5_zi4-rMx X-Proofpoint-ORIG-GUID: 3sWKm3k6UXgfSfcunPfsLO6XWtqpMRaY X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-05-18_06,2022-05-17_02,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 phishscore=0 mlxlogscore=999 adultscore=0 bulkscore=0 spamscore=0 impostorscore=0 clxscore=1011 malwarescore=0 priorityscore=1501 suspectscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2205180118 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Rob Herring , Prakhar Srivastava , Lakshmi Ramasubramanian , Vaibhav Jain , Frank Rowand , Thiago Jung Bauermann Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" Presently ima_get_kexec_buffer() doesn't check if the previous kernel's ima-kexec-buffer lies outside the addressable memory range. This can result in a kernel panic if the new kernel is booted with 'mem=X' arg and the ima-kexec-buffer was allocated beyond that range by the previous kernel. The panic is usually of the form below: $ sudo kexec --initrd initrd vmlinux --append='mem=16G' BUG: Unable to handle kernel data access on read at 0xc000c01fff7f0000 Faulting instruction address: 0xc000000000837974 Oops: Kernel access of bad area, sig: 11 [#1] NIP [c000000000837974] ima_restore_measurement_list+0x94/0x6c0 LR [c00000000083b55c] ima_load_kexec_buffer+0xac/0x160 Call Trace: [c00000000371fa80] [c00000000083b55c] ima_load_kexec_buffer+0xac/0x160 [c00000000371fb00] [c0000000020512c4] ima_init+0x80/0x108 [c00000000371fb70] [c0000000020514dc] init_ima+0x4c/0x120 [c00000000371fbf0] [c000000000012240] do_one_initcall+0x60/0x2c0 [c00000000371fcc0] [c000000002004ad0] kernel_init_freeable+0x344/0x3ec [c00000000371fda0] [c0000000000128a4] kernel_init+0x34/0x1b0 [c00000000371fe10] [c00000000000ce64] ret_from_kernel_thread+0x5c/0x64 Instruction dump: f92100b8 f92100c0 90e10090 910100a0 4182050c 282a0017 3bc00000 40810330 7c0802a6 fb610198 7c9b2378 f80101d0 2c090001 40820614 e9240010 ---[ end trace 0000000000000000 ]--- Fix this issue by checking returned address/size of previous kernel's ima-kexec-buffer against memblock's memory bounds. Fixes: fee3ff99bc67("powerpc: Move arch independent ima kexec functions to drivers/of/kexec.c") Cc: Frank Rowand Cc: Prakhar Srivastava Cc: Lakshmi Ramasubramanian Cc: Thiago Jung Bauermann Cc: Rob Herring Signed-off-by: Vaibhav Jain Reviewed-by: Lakshmi Ramasubramanian --- drivers/of/kexec.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c index b9bd1cff1793..c73007eda52d 100644 --- a/drivers/of/kexec.c +++ b/drivers/of/kexec.c @@ -140,6 +140,13 @@ int ima_get_kexec_buffer(void **addr, size_t *size) if (ret) return ret; + /* if the ima-kexec-buffer goes beyond the addressable memory */ + if (!memblock_is_region_memory(tmp_addr, tmp_size)) { + pr_warn("IMA buffer at 0x%lx, size = 0x%zx beyond memory\n", + tmp_addr, tmp_size); + return -EINVAL; + } + *addr = __va(tmp_addr); *size = tmp_size;