@@ -1029,7 +1029,8 @@ grow_dev_page(struct block_device *bdev, sector_t block,
bh = page_buffers(page);
if (bh->b_size == size) {
end_block = init_page_buffers(page, bdev,
- index << sizebits, size);
+ (sector_t)index << sizebits,
+ size);
goto done;
}
if (!try_to_free_buffers(page))
@@ -1050,7 +1051,8 @@ grow_dev_page(struct block_device *bdev, sector_t block,
*/
spin_lock(&inode->i_mapping->private_lock);
link_dev_buffers(page, bh);
- end_block = init_page_buffers(page, bdev, index << sizebits, size);
+ end_block = init_page_buffers(page, bdev, (sector_t)index << sizebits,
+ size);
spin_unlock(&inode->i_mapping->private_lock);
done:
ret = (block < end_block) ? 1 : -ENXIO;
This is a note to let you know that I have just added a patch titled Fix nasty 32-bit overflow bug in buffer i/o code. to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11.9. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 4af07654bc52583be547b2ac7cbdb6f404eec9c2 Mon Sep 17 00:00:00 2001 From: Anton Altaparmakov <aia21@cam.ac.uk> Date: Mon, 22 Sep 2014 01:53:03 +0100 Subject: Fix nasty 32-bit overflow bug in buffer i/o code. commit f2d5a94436cc7cc0221b9a81bba2276a25187dd3 upstream. On 32-bit architectures, the legacy buffer_head functions are not always handling the sector number with the proper 64-bit types, and will thus fail on 4TB+ disks. Any code that uses __getblk() (and thus bread(), breadahead(), sb_bread(), sb_breadahead(), sb_getblk()), and calls it using a 64-bit block on a 32-bit arch (where "long" is 32-bit) causes an inifinite loop in __getblk_slow() with an infinite stream of errors logged to dmesg like this: __find_get_block_slow() failed. block=6740375944, b_blocknr=2445408648 b_state=0x00000020, b_size=512 device sda1 blocksize: 512 Note how in hex block is 0x191C1F988 and b_blocknr is 0x91C1F988 i.e. the top 32-bits are missing (in this case the 0x1 at the top). This is because grow_dev_page() is broken and has a 32-bit overflow due to shifting the page index value (a pgoff_t - which is just 32 bits on 32-bit architectures) left-shifted as the block number. But the top bits to get lost as the pgoff_t is not type cast to sector_t / 64-bit before the shift. This patch fixes this issue by type casting "index" to sector_t before doing the left shift. Note this is not a theoretical bug but has been seen in the field on a 4TiB hard drive with logical sector size 512 bytes. This patch has been verified to fix the infinite loop problem on 3.17-rc5 kernel using a 4TB disk image mounted using "-o loop". Without this patch doing a "find /nt" where /nt is an NTFS volume causes the inifinite loop 100% reproducibly whilst with the patch it works fine as expected. Signed-off-by: Anton Altaparmakov <aia21@cantab.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- fs/buffer.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) -- 1.9.1