lkml.org 
[lkml]   [2016]   [Sep]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v3 4/9] arm64: alternative: Disallow patching instructions using literals
    Date
    The alternative code patching doesn't check if the replaced instruction
    uses a pc relative literal. This could cause silent corruption in the
    instruction stream as the instruction will be executed from a different
    address than what it was compiled for. Catch all such cases.

    Cc: Marc Zyngier <marc.zyngier@arm.com>
    Cc: Andre Przywara <andre.przywara@arm.com>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Suggested-by: Will Deacon <will.deacon@arm.com>
    Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
    ---
    arch/arm64/kernel/alternative.c | 6 ++++++
    1 file changed, 6 insertions(+)

    diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
    index 4434dab..992918d 100644
    --- a/arch/arm64/kernel/alternative.c
    +++ b/arch/arm64/kernel/alternative.c
    @@ -79,6 +79,12 @@ static u32 get_alt_insn(struct alt_instr *alt, u32 *insnptr, u32 *altinsnptr)
    offset = target - (unsigned long)insnptr;
    insn = aarch64_set_branch_offset(insn, offset);
    }
    + } else if (aarch64_insn_uses_literal(insn)) {
    + /*
    + * Disallow patching unhandled instructions using PC relative
    + * literal addresses
    + */
    + BUG();
    }

    return insn;
    --
    2.7.4
    \
     
     \ /
      Last update: 2016-09-17 09:58    [W:4.352 / U:0.136 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site