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charset=us-ascii Content-Disposition: inline In-Reply-To: <20260123030238.835748-1-tujinjiang@huawei.com> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 7C235C0004 X-Stat-Signature: dpr7rb1yen6d1m93c9rkkd8ieqip6xht X-HE-Tag: 1769193373-345921 X-HE-Meta: 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 L2sv1giW w1Ch/u9HaiN+nZNUYG3Y9adUznw5WU2Vapubtbw01EeFtR9BtNzYa8yu7Dzi2I32BVp2WBWNAU15xRxKP1whDlta0rZzGeg8CoAgRKs9Ba69hgdhSObjLkf92CrvB4hEtxlGt7OKhU4cGXmcHeZDlXbS93Gwqn7g+3dmaEEnTKtN3Sbdz/VycKgiIuUW2UVThBQk3lvceGHQQ0t6HdTLJBWVcIQ== 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: On Fri, Jan 23, 2026 at 11:02:38AM +0800, Jinjiang Tu wrote: > 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. generic_access_phys() is really weird - it takes the user PTE attributes and passes them to the kernel ioremap_prot(), hoping for the best. My immediate thought was to fix this in the core code. However, we also need to preserve the original memory type from vma->vm_page_prot and I don't think we have any generic macros to just preserve the attributes but with kernel permissions (pte_mkkernel?). -- Catalin