x86/fpu/xsaves: Fix improper uses of __ex_table

Commit:

  f31a9f7c7169 ("x86/xsaves: Use xsaves/xrstors to save and restore xsave area")

introduced alternative instructions for XSAVES/XRSTORS and commit:

  adb9d526e982 ("x86/xsaves: Add xsaves and xrstors support for booting time")

added support for the XSAVES/XRSTORS instructions at boot time.

Unfortunately both failed to properly protect them against faulting:

The 'xstate_fault' macro will use the closest label named '1'
backward and that ends up in the .altinstr_replacement section
rather than in .text. This means that the kernel will never find
in the __ex_table the .text address where this instruction might
fault, leading to serious problems if userspace manages to
trigger the fault.

Signed-off-by: Quentin Casasnovas <[email protected]>
Signed-off-by: Jamie Iles <[email protected]>
[ Improved the changelog, fixed some whitespace noise. ]
Acked-by: Borislav Petkov <[email protected]>
Acked-by: Linus Torvalds <[email protected]>
Cc: <[email protected]>
Cc: Allan Xavier <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: adb9d526e982 ("x86/xsaves: Add xsaves and xrstors support for booting time")
Fixes: f31a9f7c7169 ("x86/xsaves: Use xsaves/xrstors to save and restore xsave area")
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions