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authorRussell King <rmk+kernel@arm.linux.org.uk>2015-05-15 11:02:23 +0100
committerSasha Levin <sasha.levin@oracle.com>2015-06-10 13:42:33 -0400
commit40b09824118a183f5ab0f6d4161911d505e62ee8 (patch)
parent62267afe2eb7bddbd98b7f15756623156df4456c (diff)
ARM: fix missing syscall trace exit
[ Upstream commit 1b97937246d8b97c0760d16d8992c7937bdf5e6a ] 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: Sasha Levin <sasha.levin@oracle.com>
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 6bb09d4abdea..eb6f1927b2c7 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