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Fri, 23 Jan 2026 11:03:44 +0800 (CST) Received: from kwepemr500001.china.huawei.com (unknown [7.202.194.229]) by mail.maildlp.com (Postfix) with ESMTPS id 7969A40565; Fri, 23 Jan 2026 11:07:09 +0800 (CST) Received: from huawei.com (10.50.85.135) by kwepemr500001.china.huawei.com (7.202.194.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 23 Jan 2026 11:07:08 +0800 From: Jinjiang Tu To: , , , , , , , , , , Subject: [PATCH] arm64: mm: explicitly use kernel pte for ioremap_prot() Date: Fri, 23 Jan 2026 11:02:38 +0800 Message-ID: <20260123030238.835748-1-tujinjiang@huawei.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.50.85.135] X-ClientProxiedBy: kwepems200002.china.huawei.com (7.221.188.68) To kwepemr500001.china.huawei.com (7.202.194.229) X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 163DA18000C X-Stat-Signature: 8f3tcidbxzgdbiskbswtocexg1t7dkum X-Rspam-User: X-HE-Tag: 1769137634-499620 X-HE-Meta: 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 eyfu7bP4 e2toZz/HxsT7RYjC0rY6mZgY/XFol2GwwT28TbfrI/dLcRoiYo54kB2OgdoS20ycpZ/5GRyFV4gHunJbJnYXEu4/s6nKP+7RCpB15XWT9c/Z8jeHJ2Yw1XDJuXda2cYteRoYP0AZRQoc95NTQB4t1TXuVA1V0rii4MLK+Gwv759rH+aRdnz4v2AUddQysJPotzzcsr9IwUFK3LHuAQet8kW7tH++p+v4giVsgYZNkm87JOT2IXUlQaxeke9E+ve+yRoH7J1XIAGxnZVZkcrDYuAMcqGiFYWyxhsOpJUl5xDUHB8FNsBWqeaJsIPgFfFvzGRkt0kCAFAIeFz0wedF+pNc+iw== 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: List-Subscribe: List-Unsubscribe: Here is a syzkaller error log: [0000000020ffc000] pgd=080000010598d403, p4d=080000010598d403, pud=0800000125ddb403, pmd=080000007833c403, pte=01608000007fcfcf Unable to handle kernel read from unreadable memory at virtual address ffff80008ea89000 KASAN: probably user-memory-access in range [0x0000000475448000-0x0000000475448007] Mem abort info: ESR = 0x000000009600000f EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x0f: level 3 permission fault Data abort info: ISV = 0, ISS = 0x0000000f, ISS2 = 0x00000000 CM = 0, WnR = 0, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000001244aa000 [ffff80008ea89000] pgd=100000013ffff403, p4d=100000013ffff403, pud=100000013fffe403, pmd=100000010a453403, pte=01608000007fcfcf Internal error: Oops: 000000009600000f [#1] SMP Modules linked in: team CPU: 1 PID: 10840 Comm: syz.9.83 Kdump: loaded Tainted: G Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 pstate: 20400005 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : __memcpy_fromio+0x80/0xf8 lr : generic_access_phys+0x20c/0x2b8 sp : ffff8000a0507960 x29: ffff8000a0507960 x28: 1ffff000140a0f44 x27: ffff00003833cfe0 x26: 0000000000000000 x25: 0000000000001000 x24: 0010000000000001 x23: ffff80008ea89000 x22: ffff00004ea63000 x21: 0000000000001000 x20: ffff80008ea89000 x19: ffff00004ea62000 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: ffff8000806f1e3c x14: ffff8000806f1d44 x13: 0000000041b58ab3 x12: ffff7000140a0f23 x11: 1ffff000140a0f22 x10: ffff7000140a0f22 x9 : ffff800080579d24 x8 : 0000000000000004 x7 : 0000000000000003 x6 : 0000000000000001 x5 : ffff8000a0507910 x4 : ffff7000140a0f22 x3 : dfff800000000000 x2 : 0000000000001000 x1 : ffff80008ea89000 x0 : ffff00004ea62000 Call trace: __memcpy_fromio+0x80/0xf8 generic_access_phys+0x20c/0x2b8 __access_remote_vm+0x46c/0x5b8 access_remote_vm+0x18/0x30 environ_read+0x238/0x3e8 vfs_read+0xe4/0x2b0 ksys_read+0xcc/0x178 __arm64_sys_read+0x4c/0x68 invoke_syscall+0x68/0x1a0 el0_svc_common.constprop.0+0x11c/0x150 do_el0_svc+0x38/0x50 el0_svc+0x50/0x258 el0t_64_sync_handler+0xc0/0xc8 el0t_64_sync+0x1a4/0x1a8 Code: 91002339 aa1403f7 8b190276 d503201f (f94002f8) The local syzkaller first maps I/O address from /dev/mem to userspace, overiding the stack vma with MAP_FIXED flag. As a result, when reading /proc/$pid/environ, generic_access_phys() is called to access the region, which triggers a PAN permission-check fault and causes a kernel access fault. The root cause is that generic_access_phys() passes a user pte to ioremap_prot(), the user pte sets PTE_USER and PTE_NG bits. Consequently, any subsequent kernel-mode access to the remapped address raises a fault. To fix it, similar to ioremap_prot() in x86, use _PAGE_KERNEL as template, and update PTE_WRITE and PTE_ATTRINDX according to the pgprot argument. Fixes: 893dea9ccd08 ("arm64: Add HAVE_IOREMAP_PROT support") Signed-off-by: Zeng Heng Signed-off-by: Jinjiang Tu --- arch/arm64/mm/ioremap.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/arm64/mm/ioremap.c b/arch/arm64/mm/ioremap.c index 10e246f11271..78a63a14465f 100644 --- a/arch/arm64/mm/ioremap.c +++ b/arch/arm64/mm/ioremap.c @@ -18,6 +18,7 @@ void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size, pgprot_t pgprot) { unsigned long last_addr = phys_addr + size - 1; + unsigned long new_pgprot_val; /* Don't allow outside PHYS_MASK */ if (last_addr & ~PHYS_MASK) @@ -27,6 +28,11 @@ void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size, if (WARN_ON(pfn_is_map_memory(__phys_to_pfn(phys_addr)))) return NULL; + new_pgprot_val = _PAGE_KERNEL & ~(PTE_WRITE | PTE_ATTRINDX_MASK); + new_pgprot_val |= (pgprot_val(pgprot) & PTE_WRITE) + | (pgprot_val(pgprot) & PTE_ATTRINDX_MASK); + pgprot = __pgprot(new_pgprot_val); + /* * If a hook is registered (e.g. for confidential computing * purposes), call that now and barf if it fails. -- 2.43.0