| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 087/110] ARM: fix missing syscall trace exit | Date | Fri, 5 Jun 2015 14:58:10 +0100 |
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3.16.7-ckt13 -stable review patch. If anyone has any objections, please let me know.
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From: Russell King <rmk+kernel@arm.linux.org.uk>
commit 1b97937246d8b97c0760d16d8992c7937bdf5e6a upstream.
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 <jistone@redhat.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- arch/arm/kernel/entry-common.S | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 7139d4a7dea7..29b81fc959fe 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -32,7 +32,9 @@ 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
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