From: Vincenzo Frascino <vincenzo.frasc...@arm.com>
commit d263119387de9975d2acba1dfd3392f7c5979c18 upstream.
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.mari...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Jann Horn <ja...@google.com>
Cc: <sta...@vger.kernel.org>
Reported-by: Jann Horn <ja...@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frasc...@arm.com>
[will: fixed typo in comment]
Signed-off-by: Will Deacon <will.dea...@arm.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/arm64/include/asm/processor.h | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -53,7 +53,15 @@
* TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area.
*/
#ifdef CONFIG_COMPAT
+#ifdef CONFIG_ARM64_64K_PAGES
+/*
+ * With CONFIG_ARM64_64K_PAGES enabled, the last page is occupied
+ * by the compat vectors page.
+ */
#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) ? \
