x86/static_call: Fix __static_call_fixup()

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commit 5409730962 upstream.

Christian reported spurious module load crashes after some of Song's
module memory layout patches.

Turns out that if the very last instruction on the very last page of the
module is a 'JMP __x86_return_thunk' then __static_call_fixup() will
trip a fault and die.

And while the module rework made this slightly more likely to happen,
it's always been possible.

Fixes: ee88d363d1 ("x86,static_call: Use alternative RET encoding")
Reported-by: Christian Bricart <christian@bricart.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lkml.kernel.org/r/20230816104419.GA982867@hirez.programming.kicks-ass.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Peter Zijlstra 2023-08-16 12:44:19 +02:00 • committed by Greg Kroah-Hartman

parent 37e6d8509c

commit 92588f22a2

1 changed files with 13 additions and 0 deletions

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arch/x86/kernel/static_call.c

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