| From | Linus Torvalds <> | Date | Tue, 23 May 2017 13:21:15 -0700 | Subject | Re: [PATCH 4.11 044/197] x86: fix 32-bit case of __get_user_asm_u64() |
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On Tue, May 23, 2017 at 1:06 PM, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > 4.11-stable review patch. If anyone has any objections, please let me know.
No objections, but I do want to note that I verified with a "allyesconfig" build on i386 that this code actually never triggers at least in current -git. I might have screwed something up, but I added a "fsin" instruction to that inline asm, and then verified that "objdump" didn't find any fsin instructions in any object files after the build.
There are people who do 64-bit reads from user space, but they all seem to happily use "get_user()" that gets it right, not the "__get_user()" helper that did not.
So it's still worth putting in stable (just in case of future or external users), but at least it doesn't seem to be a potential security issue (which it might have been - with the right unlucky code generation you could make the 64-bit load basically be a pointer following thing).
Linus
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