Messages in this thread Patch in this message | | | Date | Thu, 17 Sep 2015 22:24:16 -0400 | From | Sasha Levin <> | Subject | Re: fs: out of bounds on stack in iov_iter_advance |
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On 08/19/2015 01:46 AM, Al Viro wrote: >> or mapping->a_ops->direct_IO() returned more >> > than 'count'. > Was there DAX involved? ->direct_IO() in there is blkdev_direct_IO(), > which takes rather different paths in those cases... >
So I've traced this all the way back to dax_io(). I can trigger this with:
diff --git a/fs/dax.c b/fs/dax.c index 93bf2f9..2cdb8a5 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -178,6 +178,7 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, if (need_wmb) wmb_pmem();
+ WARN_ON((pos == start) && (pos - start > iov_iter_count(iter))); return (pos == start) ? retval : pos - start; }
So it seems that iter gets moved twice here: once in dax_io(), and once again back at generic_file_read_iter(). I don't see how it ever worked. Am I missing something?
Thanks, Sasha
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