hulk inclusion category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/8982 ---------------------------------------- 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, define arch_mk_kernel_prot() to convert user prot to kernel prot for arm64, and call arch_mk_kernel_prot() in generic_access_phys(), so that a user prot is passed to ioremap_prot(). Mainline kernel fixes this issue by commit f6bf47ab32e0 ("arm64: io: Rename ioremap_prot() to __ioremap_prot()") and commit 8f098037139b ("arm64: io: Extract user memory type in ioremap_prot()"), which breaks KABI. So don't fix with the mainline kernel approach. Fixes: 893dea9ccd08 ("arm64: Add HAVE_IOREMAP_PROT support") Signed-off-by: Zeng Heng <zengheng4@huawei.com> Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- arch/arm64/include/asm/io.h | 11 +++++++++++ mm/memory.c | 14 ++++++++++++-- 2 files changed, 23 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h index e9d6bcfddf35..227c16c8fc1d 100644 --- a/arch/arm64/include/asm/io.h +++ b/arch/arm64/include/asm/io.h @@ -146,6 +146,17 @@ int arm64_ioremap_prot_hook_register(const ioremap_prot_hook_t hook); #define ioremap_prot ioremap_prot +#define arch_mk_kernel_prot arch_mk_kernel_prot +static inline unsigned long arch_mk_kernel_prot(unsigned long user_prot) +{ + unsigned long kernel_prot_val; + + kernel_prot_val = _PAGE_KERNEL & ~PTE_ATTRINDX_MASK; + kernel_prot_val |= user_prot & PTE_ATTRINDX_MASK; + + return kernel_prot_val; +} + #define _PAGE_IOREMAP PROT_DEVICE_nGnRE #define ioremap_wc(addr, size) \ diff --git a/mm/memory.c b/mm/memory.c index 794233ef55eb..28de289fe973 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -6536,6 +6536,14 @@ int follow_phys(struct vm_area_struct *vma, return ret; } +#ifndef arch_mk_kernel_prot +#define arch_mk_kernel_prot arch_mk_kernel_prot +static inline unsigned long arch_mk_kernel_prot(unsigned long user_prot) +{ + return user_prot; +} +#endif + /** * generic_access_phys - generic implementation for iomem mmap access * @vma: the vma to access @@ -6552,7 +6560,8 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, void *buf, int len, int write) { resource_size_t phys_addr; - unsigned long prot = 0; + unsigned long user_prot = 0; + unsigned long prot; void __iomem *maddr; pte_t *ptep, pte; spinlock_t *ptl; @@ -6568,12 +6577,13 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, pte = ptep_get(ptep); pte_unmap_unlock(ptep, ptl); - prot = pgprot_val(pte_pgprot(pte)); + user_prot = pgprot_val(pte_pgprot(pte)); phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; if ((write & FOLL_WRITE) && !pte_write(pte)) return -EINVAL; + prot = arch_mk_kernel_prot(user_prot); maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot); if (!maddr) return -ENOMEM; -- 2.43.0