[PATCH] arm64: mm: unaligned access by user-land should be received as SIGBUS
Victor Kamensky
kamensky at cisco.com
Sun Apr 2 22:45:14 PDT 2017
After 52d7523 (arm64: mm: allow the kernel to handle alignment faults on
user accesses) commit user-land accesses that produce unaligned exceptions
like in case of aarch32 ldm/stm/ldrd/strd instructions operating on
unaligned memory received by user-land as SIGSEGV. It is wrong, it should
be reported as SIGBUS as it was before 52d7523 commit.
Changed do_bad_area function to take signal and code parameters, so caller
can pass them down properly depending on fault type, as SIGSEGV in case of
do_translation_fault and SIGBUS in case of do_alignment_fault.
Signed-off-by: Victor Kamensky <kamensky at cisco.com>
Cc: xe-linux-external at cisco.com
Fixes: 52d7523 (arm64: mm: allow the kernel to handle alignment faults on user accesses)
---
arch/arm64/mm/fault.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 4bf899f..204eb58 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -215,7 +215,8 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
force_sig_info(sig, &si, tsk);
}
-static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)
+static void do_bad_area(unsigned long addr, unsigned int esr,
+ struct pt_regs *regs, int sig, int code)
{
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->active_mm;
@@ -225,7 +226,7 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re
* handle this fault with.
*/
if (user_mode(regs))
- __do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs);
+ __do_user_fault(tsk, addr, esr, sig, code, regs);
else
__do_kernel_fault(mm, addr, esr, regs);
}
@@ -469,14 +470,14 @@ static int __kprobes do_translation_fault(unsigned long addr,
if (addr < TASK_SIZE)
return do_page_fault(addr, esr, regs);
- do_bad_area(addr, esr, regs);
+ do_bad_area(addr, esr, regs, SIGSEGV, SEGV_MAPERR);
return 0;
}
static int do_alignment_fault(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
- do_bad_area(addr, esr, regs);
+ do_bad_area(addr, esr, regs, SIGBUS, BUS_ADRALN);
return 0;
}
--
1.9.3
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