+ maccess-return-erange-when-copy_from_kernel_nofault_allowed-fails.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: maccess: return -ERANGE when probe_kernel_read() fails
has been added to the -mm tree.  Its filename is
     maccess-return-erange-when-copy_from_kernel_nofault_allowed-fails.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/maccess-return-erange-when-copy_from_kernel_nofault_allowed-fails.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/maccess-return-erange-when-copy_from_kernel_nofault_allowed-fails.patch

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------------------------------------------------------
From: Christoph Hellwig <hch@lst.de>
Subject: maccess: return -ERANGE when probe_kernel_read() fails

Allow the callers to distinguish a real unmapped address vs a range
that can't be probed.

Link: http://lkml.kernel.org/r/20200521152301.2587579-24-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/maccess.c |   16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

--- a/mm/maccess.c~maccess-return-erange-when-copy_from_kernel_nofault_allowed-fails
+++ a/mm/maccess.c
@@ -24,7 +24,7 @@ bool __weak probe_kernel_read_allowed(co
 long probe_kernel_read(void *dst, const void *src, size_t size)
 {
 	if (!probe_kernel_read_allowed(src, size))
-		return -EFAULT;
+		return -ERANGE;
 
 	pagefault_disable();
 	probe_kernel_read_loop(dst, src, size, u64, Efault);
@@ -68,7 +68,7 @@ long strncpy_from_kernel_nofault(char *d
 	if (unlikely(count <= 0))
 		return 0;
 	if (!probe_kernel_read_allowed(unsafe_addr, count))
-		return -EFAULT;
+		return -ERANGE;
 
 	pagefault_disable();
 	do {
@@ -93,7 +93,8 @@ Efault:
  * @size: size of the data chunk
  *
  * Safely read from kernel address @src to the buffer at @dst.  If a kernel
- * fault happens, handle that and return -EFAULT.
+ * fault happens, handle that and return -EFAULT.  If @src is not a valid kernel
+ * address, return -ERANGE.
  *
  * We ensure that the copy_from_user is executed in atomic context so that
  * do_page_fault() doesn't attempt to take mmap_lock.  This makes
@@ -106,7 +107,7 @@ long probe_kernel_read(void *dst, const
 	mm_segment_t old_fs = get_fs();
 
 	if (!probe_kernel_read_allowed(src, size))
-		return -EFAULT;
+		return -ERANGE;
 
 	set_fs(KERNEL_DS);
 	pagefault_disable();
@@ -158,8 +159,9 @@ long probe_kernel_write(void *dst, const
  *
  * On success, returns the length of the string INCLUDING the trailing NUL.
  *
- * If access fails, returns -EFAULT (some data may have been copied
- * and the trailing NUL added).
+ * If access fails, returns -EFAULT (some data may have been copied and the
+ * trailing NUL added).  If @unsafe_addr is not a valid kernel address, return
+ * -ERANGE.
  *
  * If @count is smaller than the length of the string, copies @count-1 bytes,
  * sets the last byte of @dst buffer to NUL and returns @count.
@@ -173,7 +175,7 @@ long strncpy_from_kernel_nofault(char *d
 	if (unlikely(count <= 0))
 		return 0;
 	if (!probe_kernel_read_allowed(unsafe_addr, count))
-		return -EFAULT;
+		return -ERANGE;
 
 	set_fs(KERNEL_DS);
 	pagefault_disable();
_

Patches currently in -mm which might be from hch@lst.de are

x86-hyperv-use-vmalloc_exec-for-the-hypercall-page.patch
x86-fix-vmap-arguments-in-map_irq_stack.patch
staging-android-ion-use-vmap-instead-of-vm_map_ram.patch
staging-media-ipu3-use-vmap-instead-of-reimplementing-it.patch
dma-mapping-use-vmap-insted-of-reimplementing-it.patch
powerpc-add-an-ioremap_phb-helper.patch
powerpc-remove-__ioremap_at-and-__iounmap_at.patch
mm-remove-__get_vm_area.patch
mm-unexport-unmap_kernel_range_noflush.patch
mm-rename-config_pgtable_mapping-to-config_zsmalloc_pgtable_mapping.patch
mm-only-allow-page-table-mappings-for-built-in-zsmalloc.patch
mm-pass-addr-as-unsigned-long-to-vb_free.patch
mm-remove-vmap_page_range_noflush-and-vunmap_page_range.patch
mm-rename-vmap_page_range-to-map_kernel_range.patch
mm-dont-return-the-number-of-pages-from-map_kernel_range_noflush.patch
mm-remove-map_vm_range.patch
mm-remove-unmap_vmap_area.patch
mm-remove-the-prot-argument-from-vm_map_ram.patch
mm-enforce-that-vmap-cant-map-pages-executable.patch
gpu-drm-remove-the-powerpc-hack-in-drm_legacy_sg_alloc.patch
mm-remove-the-pgprot-argument-to-__vmalloc.patch
mm-remove-the-prot-argument-to-__vmalloc_node.patch
mm-remove-both-instances-of-__vmalloc_node_flags.patch
mm-remove-__vmalloc_node_flags_caller.patch
mm-switch-the-test_vmalloc-module-to-use-__vmalloc_node.patch
mm-remove-vmalloc_user_node_flags.patch
arm64-use-__vmalloc_node-in-arch_alloc_vmap_stack.patch
powerpc-use-__vmalloc_node-in-alloc_vm_stack.patch
s390-use-__vmalloc_node-in-stack_alloc.patch
exec-simplify-the-copy_strings_kernel-calling-convention.patch
exec-open-code-copy_string_kernel.patch
amdgpu-a-null-mm-does-not-mean-a-thread-is-a-kthread.patch
kernel-move-use_mm-unuse_mm-to-kthreadc.patch
kernel-move-use_mm-unuse_mm-to-kthreadc-v2.patch
kernel-better-document-the-use_mm-unuse_mm-api-contract.patch
kernel-better-document-the-use_mm-unuse_mm-api-contract-v2.patch
kernel-set-user_ds-in-kthread_use_mm.patch
arm-fix-the-flush_icache_range-arguments-in-set_fiq_handler.patch
nds32-unexport-flush_icache_page.patch
powerpc-unexport-flush_icache_user_range.patch
unicore32-remove-flush_cache_user_range.patch
asm-generic-fix-the-inclusion-guards-for-cacheflushh.patch
asm-generic-dont-include-linux-mmh-in-cacheflushh.patch
asm-generic-dont-include-linux-mmh-in-cacheflushh-fix.patch
asm-generic-improve-the-flush_dcache_page-stub.patch
alpha-use-asm-generic-cacheflushh.patch
arm64-use-asm-generic-cacheflushh.patch
c6x-use-asm-generic-cacheflushh.patch
hexagon-use-asm-generic-cacheflushh.patch
ia64-use-asm-generic-cacheflushh.patch
microblaze-use-asm-generic-cacheflushh.patch
m68knommu-use-asm-generic-cacheflushh.patch
openrisc-use-asm-generic-cacheflushh.patch
powerpc-use-asm-generic-cacheflushh.patch
riscv-use-asm-generic-cacheflushh.patch
armsparcunicore32-remove-flush_icache_user_range.patch
mm-rename-flush_icache_user_range-to-flush_icache_user_page.patch
asm-generic-add-a-flush_icache_user_range-stub.patch
sh-implement-flush_icache_user_range.patch
xtensa-implement-flush_icache_user_range.patch
arm-rename-flush_cache_user_range-to-flush_icache_user_range.patch
m68k-implement-flush_icache_user_range.patch
exec-only-build-read_code-when-needed.patch
exec-use-flush_icache_user_range-in-read_code.patch
binfmt_flat-use-flush_icache_user_range.patch
nommu-use-flush_icache_user_range-in-brk-and-mmap.patch
module-move-the-set_fs-hack-for-flush_icache_range-to-m68k.patch
maccess-unexport-probe_kernel_write-and-probe_user_write.patch
maccess-remove-various-unused-weak-aliases.patch
maccess-remove-duplicate-kerneldoc-comments.patch
maccess-clarify-kerneldoc-comments.patch
maccess-update-the-top-of-file-comment.patch
maccess-rename-strncpy_from_unsafe_user-to-strncpy_from_user_nofault.patch
maccess-rename-strncpy_from_unsafe_strict-to-strncpy_from_kernel_nofault.patch
maccess-rename-strnlen_unsafe_user-to-strnlen_user_nofault.patch
maccess-remove-probe_read_common-and-probe_write_common.patch
maccess-unify-the-probe-kernel-arch-hooks.patch
bpf-factor-out-a-bpf_trace_copy_string-helper.patch
bpf-handle-the-compat-string-in-bpf_trace_copy_string-better.patch
bpf-rework-the-compat-kernel-probe-handling.patch
tracing-kprobes-handle-mixed-kernel-userspace-probes-better.patch
maccess-remove-strncpy_from_unsafe.patch
maccess-always-use-strict-semantics-for-probe_kernel_read.patch
maccess-move-user-access-routines-together.patch
maccess-allow-architectures-to-provide-kernel-probing-directly.patch
x86-use-non-set_fs-based-maccess-routines.patch
maccess-return-erange-when-copy_from_kernel_nofault_allowed-fails.patch