From: Russell King Date: Fri, 15 May 2015 10:02:23 +0000 (+0100) Subject: ARM: fix missing syscall trace exit X-Git-Tag: firefly_0821_release~176^2~1703^2~1 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=1b97937246d8b97c0760d16d8992c7937bdf5e6a;p=firefly-linux-kernel-4.4.55.git ARM: fix missing syscall trace exit Josh Stone reports: I've discovered a case where both arm and arm64 will miss a ptrace syscall-exit that they should report. If the syscall is entered without TIF_SYSCALL_TRACE set, then it goes on the fast path. It's then possible to have TIF_SYSCALL_TRACE added in the middle of the syscall, but ret_fast_syscall doesn't check this flag again. Fix this by always checking for a syscall trace in the fast exit path. Reported-by: Josh Stone Signed-off-by: Russell King --- diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index f8ccc21fa032..4e7f40c577e6 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -33,7 +33,9 @@ ret_fast_syscall: UNWIND(.fnstart ) UNWIND(.cantunwind ) disable_irq @ disable interrupts - ldr r1, [tsk, #TI_FLAGS] + ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing + tst r1, #_TIF_SYSCALL_WORK + bne __sys_trace_return tst r1, #_TIF_WORK_MASK bne fast_work_pending asm_trace_hardirqs_on