alt Hacker NewsFrom your previous post:
>It's user data in JSON in an HTTP stream in a TLS record in a TCP stream in an IP packet in an ethernet frame. Then it goes into a SQL query which goes into a B-tree node which goes into a filesystem extent which goes into a RAID stripe which goes into a logical block mapped to a physical block etc. All of those have control data in the same stream under the hood.
It's true that a lot of code out there has bugs with escape sequences or field lengths, and some protocols may be designed so badly that it may be impossible to avoid such bugs. But what you are suggesting is greatly exaggerated, especially when we get to the lower layers. There is almost certainly no way that writing a "magic" byte sequence to a file will cause the storage device to misinterpret it as control data and change the mapping of logical to physical blocks. They've figured out how to separate this information reliably back when we were using floppy disks.
That the bits which control the block mapping are stored on the same device as a record in an SQL database doesn't mean that both are "the same stream".
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> There is almost certainly no way that writing a "magic" byte sequence to a file will cause the storage device to misinterpret it as control data and change the mapping of logical to physical blocks.
Which is also what happens if you use parameterized SQL queries. Or not what happens when one of the lower layers has a bug, like Heartbleed.
There also have been several disk firmware bugs over the years in various models where writing a specific data pattern results in corruption because the drive interprets it as an internal sequence.
I distinctly remember bugs with non-Hayes modems where they would treat `+++ATH0` coming over the wire as a control, leading to BBS messages which could forcibly disconnect the unlucky user who read it.
In this particular case, IIRC Hayes had patented the known approach for detecting this and avoiding the disconnect, so rival modem makers were somewhat powerless to do anything better. I wonder if such a patent would still hold today...