From 2404269bc4e77a67875c8db6667be34c9913c96e Mon Sep 17 00:00:00 2001 From: Thomas Garnier Date: Thu, 7 Sep 2017 08:30:45 -0700 Subject: Revert "arm/syscalls: Check address limit on user-mode return" This reverts commit 73ac5d6a2b6ac3ae8d1e1818f3e9946f97489bc9. The work pending loop can call set_fs after addr_limit_user_check removed the _TIF_FSCHECK flag. This may happen at anytime based on how ARM handles alignment exceptions. It leads to an infinite loop condition. After discussion, it has been agreed that the generic approach is not tailored to the ARM architecture and any fix might not be complete. This patch will be replaced by an architecture specific implementation. The work flag approach will be kept for other architectures. Reported-by: Leonard Crestez Signed-off-by: Thomas Garnier Signed-off-by: Kees Cook Signed-off-by: Thomas Gleixner Cc: Pratyush Anand Cc: Dave Martin Cc: Will Drewry Cc: Arnd Bergmann Cc: Catalin Marinas Cc: Will Deacon Cc: Russell King Cc: Andy Lutomirski Cc: David Howells Cc: Dave Hansen Cc: Al Viro Cc: linux-api@vger.kernel.org Cc: Yonghong Song Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1504798247-48833-3-git-send-email-keescook@chromium.org --- arch/arm/kernel/entry-common.S | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) (limited to 'arch/arm/kernel/entry-common.S') diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index ca3614dc6938..0b60adf4a5d9 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -49,9 +49,7 @@ ret_fast_syscall: UNWIND(.cantunwind ) disable_irq_notrace @ disable interrupts ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing - tst r1, #_TIF_SYSCALL_WORK - bne fast_work_pending - tst r1, #_TIF_WORK_MASK + tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK bne fast_work_pending /* perform architecture specific actions before user return */ @@ -77,15 +75,12 @@ ret_fast_syscall: str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 disable_irq_notrace @ disable interrupts ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing - tst r1, #_TIF_SYSCALL_WORK - bne fast_work_pending - tst r1, #_TIF_WORK_MASK + tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK beq no_work_pending UNWIND(.fnend ) ENDPROC(ret_fast_syscall) /* Slower path - fall through to work_pending */ -fast_work_pending: #endif tst r1, #_TIF_SYSCALL_WORK -- cgit