]> git.itanic.dy.fi Git - linux-stable/commit
x86/nospec: Fix i386 RSB stuffing
authorPeter Zijlstra <peterz@infradead.org>
Fri, 19 Aug 2022 11:01:35 +0000 (13:01 +0200)
committerPeter Zijlstra <peterz@infradead.org>
Fri, 19 Aug 2022 11:24:33 +0000 (13:24 +0200)
commit332924973725e8cdcc783c175f68cf7e162cb9e5
treeb76aac38d4f92e8851fe474a237195aed5607373
parent4e3aa9238277597c6c7624f302d81a7b568b6f2d
x86/nospec: Fix i386 RSB stuffing

Turns out that i386 doesn't unconditionally have LFENCE, as such the
loop in __FILL_RETURN_BUFFER isn't actually speculation safe on such
chips.

Fixes: ba6e31af2be9 ("x86/speculation: Add LFENCE to RSB fill sequence")
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/Yv9tj9vbQ9nNlXoY@worktop.programming.kicks-ass.net
arch/x86/include/asm/nospec-branch.h