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0b86dbf675
blkdev_read_iter() wants to cap the iov_iter by the amount of data remaining to the end of device. That's what iov_iter_truncate() is for (trim iter->count if it's above the given limit). So far, so good, but the argument of iov_iter_truncate() is size_t, so on 32bit boxen (in case of a large device) we end up with that upper limit truncated down to 32 bits *before* comparing it with iter->count. Easily fixed by making iov_iter_truncate() take 64bit argument - it does the right thing after such change (we only reach the assignment in there when the current value of iter->count is greater than the limit, i.e. for anything that would get truncated we don't reach the assignment at all) and that argument is not the new value of iter->count - it's an upper limit for such. The overhead of passing u64 is not an issue - the thing is inlined, so callers passing size_t won't pay any penalty. Reported-and-tested-by: Theodore Tso <tytso@mit.edu> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Tested-by: Bruno Wolff III <bruno@wolff.to> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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