3.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Catalin Marinas <catalin.mari...@arm.com>
commit 0e7f7bcc3fc87489cda5aa6aff8ce40eed912279 upstream.
ESR.WnR bit is always set on data cache maintenance faults even though
the page is not required to have write permission. If a translation
fault (page not yet mapped) happens for read-only user address range,
Linux incorrectly assumes a permission fault. This patch adds the check
of the ESR.CM bit during the page fault handling to ignore the 'write'
flag.
Signed-off-by: Catalin Marinas <catalin.mari...@arm.com>
Reported-by: Tim Northover <tim.northo...@arm.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/arm64/mm/fault.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -148,6 +148,7 @@ void do_bad_area(unsigned long addr, uns
#define VM_FAULT_BADACCESS 0x020000
#define ESR_WRITE (1 << 6)
+#define ESR_CM (1 << 8)
#define ESR_LNX_EXEC (1 << 24)
/*
@@ -206,7 +207,7 @@ static int __kprobes do_page_fault(unsig
struct task_struct *tsk;
struct mm_struct *mm;
int fault, sig, code;
- int write = esr & ESR_WRITE;
+ bool write = (esr & ESR_WRITE) && !(esr & ESR_CM);
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
(write ? FAULT_FLAG_WRITE : 0);
--
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