+ floppy-fix-max_order-usage.patch added to mm-unstable branch

+ floppy-fix-max_order-usage.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: floppy: fix MAX_ORDER usage
has been added to the -mm mm-unstable branch.  Its filename is
     floppy-fix-max_order-usage.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/floppy-fix-max_order-usage.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: floppy: fix MAX_ORDER usage
Date: Wed, 15 Mar 2023 14:31:26 +0300

MAX_ORDER is not inclusive: the maximum allocation order buddy allocator
can deliver is MAX_ORDER-1.

Fix MAX_ORDER usage in floppy code.

Also allocation buffer exactly PAGE_SIZE << MAX_ORDER bytes is okay. Fix
MAX_LEN check.

Link: https://lkml.kernel.org/r/20230315113133.11326-4-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Denis Efremov <efremov@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/floppy.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/block/floppy.c~floppy-fix-max_order-usage
+++ a/drivers/block/floppy.c
@@ -3079,7 +3079,7 @@ static void raw_cmd_free(struct floppy_r
 	}
 }
 
-#define MAX_LEN (1UL << MAX_ORDER << PAGE_SHIFT)
+#define MAX_LEN (1UL << (MAX_ORDER - 1) << PAGE_SHIFT)
 
 static int raw_cmd_copyin(int cmd, void __user *param,
 				 struct floppy_raw_cmd **rcmd)
@@ -3108,7 +3108,7 @@ loop:
 	ptr->resultcode = 0;
 
 	if (ptr->flags & (FD_RAW_READ | FD_RAW_WRITE)) {
-		if (ptr->length <= 0 || ptr->length >= MAX_LEN)
+		if (ptr->length <= 0 || ptr->length > MAX_LEN)
 			return -EINVAL;
 		ptr->kernel_data = (char *)fd_dma_mem_alloc(ptr->length);
 		fallback_on_nodma_alloc(&ptr->kernel_data, ptr->length);
_

Patches currently in -mm which might be from kirill.shutemov@linux.intel.com are

sparc-mm-fix-max_order-usage-in-tsb_grow.patch
um-fix-max_order-usage-in-linux_main.patch
floppy-fix-max_order-usage.patch
drm-i915-fix-max_order-usage-in-i915_gem_object_get_pages_internal.patch
genwqe-fix-max_order-usage.patch
perf-core-fix-max_order-usage-in-rb_alloc_aux_page.patch
mm-page_reporting-fix-max_order-usage-in-page_reporting_register.patch
mm-slub-fix-max_order-usage-in-calculate_order.patch
iommu-fix-max_order-usage-in-__iommu_dma_alloc_pages.patch
mm-treewide-redefine-max_order-sanely.patch