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[66.90.144.107]) by smtp.gmail.com with ESMTPSA id 61-20020a9d0c43000000b0060603221245sm1461293otr.21.2022.05.20.15.30.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 May 2022 15:30:26 -0700 (PDT) Received: (nullmailer pid 369508 invoked by uid 1000); Fri, 20 May 2022 22:30:25 -0000 Date: Fri, 20 May 2022 17:30:25 -0500 From: Rob Herring To: Vaibhav Jain Subject: Re: [PATCH] powerpc: check previous kernel's ima-kexec-buffer against memory bounds Message-ID: <20220520223025.GA359803-robh@kernel.org> References: <20220518200547.655788-1-vaibhav@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220518200547.655788-1-vaibhav@linux.ibm.com> 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: devicetree@vger.kernel.org, Frank Rowand , linux-kernel@vger.kernel.org, Prakhar Srivastava , Lakshmi Ramasubramanian , linuxppc-dev@lists.ozlabs.org, Thiago Jung Bauermann Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, May 19, 2022 at 01:35:47AM +0530, Vaibhav Jain wrote: > 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") Your mailer (and/or you) corrupted this. There should be a space between the commit hash and subject, and it should not be wrapped. It should also not have a blank line here. But more importantly, how did this commit introduce the problem? It just moved the code and didn't have any such check. > > Cc: Frank Rowand > Cc: Prakhar Srivastava > Cc: Lakshmi Ramasubramanian > Cc: Thiago Jung Bauermann > Cc: Rob Herring > Signed-off-by: Vaibhav Jain > --- > 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; > > -- > 2.35.1 > >