From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: stable@vger.kernel.org, Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>, Jann Horn <jannh@google.com>
Subject: [PATCH] arm64: compat: Reduce address limit
Date: Mon, 1 Apr 2019 11:32:01 +0100 [thread overview]
Message-ID: <20190401103201.9268-1-vincenzo.frascino@arm.com> (raw)
Currently, compat tasks running on arm64 can allocate memory up to
TASK_SIZE_32 (UL(0x100000000)).
This means that mmap() allocations, if we treat them as returning an
array, are not compliant with the sections 6.5.8 of the C standard
(C99) which states that: "If the expression P points to an element of
an array object and the expression Q points to the last element of the
same array object, the pointer expression Q+1 compares greater than P".
Redefine TASK_SIZE_32 to address the issue.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Jann Horn <jannh@google.com>
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
arch/arm64/include/asm/processor.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 5d9ce62bdebd..f8235f7df29b 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -57,7 +57,11 @@
#define TASK_SIZE_64 (UL(1) << vabits_user)
#ifdef CONFIG_COMPAT
+#ifdef CONFIG_ARM64_64K_PAGES
#define TASK_SIZE_32 UL(0x100000000)
+#else
+#define TASK_SIZE_32 (UL(0x100000000) - PAGE_SIZE)
+#endif /* CONFIG_ARM64_64K_PAGES */
#define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
TASK_SIZE_32 : TASK_SIZE_64)
#define TASK_SIZE_OF(tsk) (test_tsk_thread_flag(tsk, TIF_32BIT) ? \
--
2.21.0
next reply other threads:[~2019-04-01 10:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-01 10:32 Vincenzo Frascino [this message]
2019-04-01 10:32 ` [PATCH] arm64: compat: Reduce address limit Vincenzo Frascino
2019-04-01 10:59 ` Catalin Marinas
2019-04-01 10:59 ` Catalin Marinas
2019-04-01 11:27 ` Vincenzo Frascino
2019-04-01 11:27 ` Vincenzo Frascino
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