RE: [PATCH] block: create ioctl to discard-or-zeroout a range of blocks

From	"Seymour, Shane M" <shane.seymour@hpe.com>
Newsgroups	linux.kernel
Subject	RE: [PATCH] block: create ioctl to discard-or-zeroout a range of blocks
Date	2015-11-13 04:40 +0100
Message-ID	<qudnr-153-1@gated-at.bofh.it> (permalink)
References	<qt9vA-JX-11@gated-at.bofh.it> <qtwit-70n-7@gated-at.bofh.it> <qtwVb-7uA-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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> I don't have a device large enough to test for signedness errors, since passing 
> huge values for start and len never make it past the i_size_read check.

If you have someone trying to bypass your sanity checks then if start=18446744073709551104 and len=1024 the result of adding them together will be 512 (subtracting an extra 1 in the patched code to get 511 for end). That will pass the i_size_read check won't it? If so that would cause lstart in truncate_inode_pages_range() to be -512. I don't know what truncate_inode_pages_range() will do with a negative lstart value like that but it seems like an unusual value for your code to be willing to pass into truncate_inode_pages_range().

Shane
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Thread

[PATCH] block: create ioctl to discard-or-zeroout a range of blocks "Darrick J. Wong" <darrick.wong@oracle.com> - 2015-11-10 06:20 +0100
  RE: [PATCH] block: create ioctl to discard-or-zeroout a range of  blocks "Seymour, Shane M" <shane.seymour@hpe.com> - 2015-11-11 06:40 +0100
    Re: [PATCH] block: create ioctl to discard-or-zeroout a range of  blocks "Darrick J. Wong" <darrick.wong@oracle.com> - 2015-11-11 07:20 +0100
      RE: [PATCH] block: create ioctl to discard-or-zeroout a range of  blocks "Seymour, Shane M" <shane.seymour@hpe.com> - 2015-11-12 00:40 +0100
        RE: [PATCH] block: create ioctl to discard-or-zeroout a range of  blocks "Seymour, Shane M" <shane.seymour@hpe.com> - 2015-11-12 02:00 +0100
      RE: [PATCH] block: create ioctl to discard-or-zeroout a range of  blocks "Seymour, Shane M" <shane.seymour@hpe.com> - 2015-11-13 04:40 +0100
      Re: [PATCH] block: create ioctl to discard-or-zeroout a range of  blocks Jens Axboe <axboe@kernel.dk> - 2015-11-13 16:50 +0100
        Re: [PATCH] block: create ioctl to discard-or-zeroout a range of  blocks "Darrick J. Wong" <darrick.wong@oracle.com> - 2015-11-13 22:40 +0100

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