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| author | Max Filippov <jcmvbkbc@gmail.com> | 2021-02-07 15:57:58 +0300 |
|---|---|---|
| committer | Max Filippov <jcmvbkbc@gmail.com> | 2021-03-29 21:25:11 +0300 |
| commit | 7b9acbb6aad4f54623dcd4bd4b1a60fe0c727b09 (patch) | |
| tree | 370431fbaa75e42e1c97d2dec184de46005ddd9b | |
| parent | ab5eb336411f18fd449a1fb37d36a55ec422603f (diff) | |
| download | linux-7b9acbb6aad4f54623dcd4bd4b1a60fe0c727b09.tar.xz | |
xtensa: fix uaccess-related livelock in do_page_fault
If a uaccess (e.g. get_user()) triggers a fault and there's a
fault signal pending, the handler will return to the uaccess without
having performed a uaccess fault fixup, and so the CPU will immediately
execute the uaccess instruction again, whereupon it will livelock
bouncing between that instruction and the fault handler.
https://lore.kernel.org/lkml/20210121123140.GD48431@C02TD0UTHF1T.local/
Cc: stable@vger.kernel.org
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
| -rw-r--r-- | arch/xtensa/mm/fault.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c index 7666408ce12a..95a74890c7e9 100644 --- a/arch/xtensa/mm/fault.c +++ b/arch/xtensa/mm/fault.c @@ -112,8 +112,11 @@ good_area: */ fault = handle_mm_fault(vma, address, flags, regs); - if (fault_signal_pending(fault, regs)) + if (fault_signal_pending(fault, regs)) { + if (!user_mode(regs)) + goto bad_page_fault; return; + } if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) |