Messages in this thread |  | | From | David Laight <> | Subject | RE: [Xen-devel] [PATCH] [v2] xen: hypercall: fix out-of-bounds memcpy | Date | Fri, 9 Feb 2018 14:13:14 +0000 |
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From: Arnd Bergmann > Sent: 09 February 2018 12:58 ... > However, aside from this driver, I wonder if we should be worried about > Spectre type 1 attacks on similar code, when gcc-8 turns a switch/case > statement into an array lookup behind our back, e.g. in an ioctl handler. > Has anybody got this on their radar?
The canonical code for a switch statement is to jump indirect on an array of code pointers. ioctl handlers probably use a series of compares because the values are sparse.
Also remember that gcc-8 will convert dense switch statements that just load a value into a data array lookup.
I guess both those jump tables are potential attack vectors. Not quite sure how they might be used to leak info though.
David
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