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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id e8-20020a056a0000c800b0053e38ac0ff4sm3482136pfj.115.2022.12.05.16.16.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Dec 2022 16:16:24 -0800 (PST) From: Kees Cook To: Tony Luck , swboyd@chromium.org, anton@enomsg.org, ccross@android.com Cc: Kees Cook , Andrew Morton , linux-mm@kvack.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org, rppt@kernel.org, bgeffon@google.com Subject: Re: [PATCH] pstore: Avoid kcore oops by vmap()ing with VM_IOREMAP Date: Mon, 5 Dec 2022 16:16:15 -0800 Message-Id: <167028577239.2860027.4300649046470353371.b4-ty@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20221205233136.3420802-1-swboyd@chromium.org> References: <20221205233136.3420802-1-swboyd@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 0880714000C X-Stat-Signature: n6ra79ygnfghi8t5r3uopaxifi6my3d1 X-Rspam-User: X-Spamd-Result: default: False [3.73 / 9.00]; SORBS_IRL_BL(3.00)[209.85.214.175:from]; SUBJECT_HAS_UNDERSCORES(1.00)[]; BAYES_HAM(-0.37)[70.69%]; BAD_REP_POLICIES(0.10)[]; RCVD_NO_TLS_LAST(0.10)[]; MIME_GOOD(-0.10)[text/plain]; TO_MATCH_ENVRCPT_SOME(0.00)[]; DKIM_TRACE(0.00)[chromium.org:+]; DMARC_POLICY_ALLOW(0.00)[chromium.org,none]; FROM_EQ_ENVFROM(0.00)[]; RCPT_COUNT_SEVEN(0.00)[11]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_THREE(0.00)[3]; ARC_SIGNED(0.00)[hostedemail.com:s=arc-20220608:i=1]; PREVIOUSLY_DELIVERED(0.00)[linux-mm@kvack.org]; ARC_NA(0.00)[]; R_DKIM_ALLOW(0.00)[chromium.org:s=google]; MID_RHS_MATCH_FROM(0.00)[]; FROM_HAS_DN(0.00)[]; R_SPF_ALLOW(0.00)[+ip4:209.85.128.0/17]; TO_DN_SOME(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[] X-Rspamd-Server: rspam08 X-HE-Tag: 1670285786-982025 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, 5 Dec 2022 15:31:36 -0800, Stephen Boyd wrote: > An oops can be induced by running 'cat /proc/kcore > /dev/null' on > devices using pstore with the ram backend because kmap_atomic() assumes > lowmem pages are accessible with __va(). > > Unable to handle kernel paging request at virtual address ffffff807ff2b000 > Mem abort info: > ESR = 0x96000006 > EC = 0x25: DABT (current EL), IL = 32 bits > SET = 0, FnV = 0 > EA = 0, S1PTW = 0 > FSC = 0x06: level 2 translation fault > Data abort info: > ISV = 0, ISS = 0x00000006 > CM = 0, WnR = 0 > swapper pgtable: 4k pages, 39-bit VAs, pgdp=0000000081d87000 > [ffffff807ff2b000] pgd=180000017fe18003, p4d=180000017fe18003, pud=180000017fe18003, pmd=0000000000000000 > Internal error: Oops: 96000006 [#1] PREEMPT SMP > Modules linked in: dm_integrity > CPU: 7 PID: 21179 Comm: perf Not tainted 5.15.67-10882-ge4eb2eb988cd #1 baa443fb8e8477896a370b31a821eb2009f9bfba > Hardware name: Google Lazor (rev3 - 8) (DT) > pstate: a0400009 (NzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > pc : __memcpy+0x110/0x260 > lr : vread+0x194/0x294 > sp : ffffffc013ee39d0 > x29: ffffffc013ee39f0 x28: 0000000000001000 x27: ffffff807ff2b000 > x26: 0000000000001000 x25: ffffffc0085a2000 x24: ffffff802d4b3000 > x23: ffffff80f8a60000 x22: ffffff802d4b3000 x21: ffffffc0085a2000 > x20: ffffff8080b7bc68 x19: 0000000000001000 x18: 0000000000000000 > x17: 0000000000000000 x16: 0000000000000000 x15: ffffffd3073f2e60 > x14: ffffffffad588000 x13: 0000000000000000 x12: 0000000000000001 > x11: 00000000000001a2 x10: 00680000fff2bf0b x9 : 03fffffff807ff2b > x8 : 0000000000000001 x7 : 0000000000000000 x6 : 0000000000000000 > x5 : ffffff802d4b4000 x4 : ffffff807ff2c000 x3 : ffffffc013ee3a78 > x2 : 0000000000001000 x1 : ffffff807ff2b000 x0 : ffffff802d4b3000 > Call trace: > __memcpy+0x110/0x260 > read_kcore+0x584/0x778 > proc_reg_read+0xb4/0xe4 > > [...] Applied to for-next/pstore, thanks! [1/1] pstore: Avoid kcore oops by vmap()ing with VM_IOREMAP https://git.kernel.org/kees/c/e6b842741b4f -- Kees Cook