Re: [PATCH v3] block: bugfix for Amiga partition overflow check patch

Greg KH
2023-07-04T06:54:06Z

On Tue, Jul 04, 2023 at 05:49:55PM +1200, Michael Schmitz wrote:
> Making 'blk' sector_t (i.e. 64 bit if LBD support is active)
> fails the 'blk>0' test in the partition block loop if a
> value of (signed int) -1 is used to mark the end of the
> partition block list.
>
> This bug was introduced in patch 3 of my prior Amiga partition
> support fixes series, and spotted by Christian Zigotzky when
> testing the latest block updates.
>
> Explicitly cast 'blk' to signed int to allow use of -1 to
> terminate the partition block linked list.
>
> Testing by Christian also exposed another aspect of the old
> bug fixed in commits fc3d092c6b ("block: fix signed int
> overflow in Amiga partition support") and b6f3f28f60
> ("block: add overflow checks for Amiga partition support"):
>
> Partitions that did overflow the disk size (due to 32 bit int
> overflow) were not skipped but truncated to the end of the
> disk. Users who missed the warning message during boot would
> go on to create a filesystem with a size exceeding the
> actual partition size. Now that the 32 bit overflow has been
> corrected, such filesystems may refuse to mount with a
> 'filesystem exceeds partition size' error. Users should
> either correct the partition size, or resize the filesystem
> before attempting to boot a kernel with the RDB fixes in
> place.
>
> Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
> Fixes: b6f3f28f60 ("block: add overflow checks for Amiga partition support")

That commit is not in:

> Cc: <stable@vger.kernel.org> # 6.4

6.4. It's in Linus's tree only right now.

But yes, it's tagged for 5.2 and older kernels to be added to the stable
tree, so why is this one limited only to 6.4 and not also for 5.2 and
newer?

thanks,

greg k-h