From f49d5e62d9352d33b30c9befbaf0fd9c88265ec1 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 26 Jan 2007 00:57:03 -0800 Subject: [PATCH] [PATCH] md: avoid reading past the end of a bitmap file In most cases we check the size of the bitmap file before reading data from it. However when reading the superblock, we always read the first PAGE_SIZE bytes, which might not always be appropriate. So limit that read to the size of the file if appropriate. Also, we get the count of available bytes wrong in one place, so that too can read past the end of the file. Cc: "yang yin" Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/md/bitmap.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c index 5432d07c074d..11108165e264 100644 --- a/drivers/md/bitmap.c +++ b/drivers/md/bitmap.c @@ -479,9 +479,12 @@ static int bitmap_read_sb(struct bitmap *bitmap) int err = -EINVAL; /* page 0 is the superblock, read it... */ - if (bitmap->file) - bitmap->sb_page = read_page(bitmap->file, 0, bitmap, PAGE_SIZE); - else { + if (bitmap->file) { + loff_t isize = i_size_read(bitmap->file->f_mapping->host); + int bytes = isize > PAGE_SIZE ? PAGE_SIZE : isize; + + bitmap->sb_page = read_page(bitmap->file, 0, bitmap, bytes); + } else { bitmap->sb_page = read_sb_page(bitmap->mddev, bitmap->offset, 0); } if (IS_ERR(bitmap->sb_page)) { @@ -877,7 +880,8 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start) int count; /* unmap the old page, we're done with it */ if (index == num_pages-1) - count = bytes - index * PAGE_SIZE; + count = bytes + sizeof(bitmap_super_t) + - index * PAGE_SIZE; else count = PAGE_SIZE; if (index == 0) { -- 2.20.1