Commit 5f29298f authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Andrew Morton
Browse files

floppy: fix MAX_ORDER usage 

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: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarMike Rapoport (IBM) <rppt@kernel.org>
Cc: Denis Efremov <efremov@linux.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 254ca6d2

drivers/block/floppy.c

+2 −2
Original line number Diff line number Diff line
@@ -3079,7 +3079,7 @@ static void raw_cmd_free(struct floppy_raw_cmd **ptr) 
	}

}



#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 @@ static int raw_cmd_copyin(int cmd, void __user *param, 
	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);