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| author | Max Filippov <jcmvbkbc@gmail.com> | 2021-02-07 15:57:58 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-04-07 16:00:09 +0300 |
| commit | a3be911a5feed914233ec2fdc23b0103e616a142 (patch) | |
| tree | 51743337e7dc5a9835ca408a6dd2c8a6091351d2 /arch/xtensa | |
| parent | bcd7999c03ed4617dedcf9b2ad09a6e7f7cf5150 (diff) | |
| download | linux-a3be911a5feed914233ec2fdc23b0103e616a142.tar.xz | |
xtensa: fix uaccess-related livelock in do_page_fault
commit 7b9acbb6aad4f54623dcd4bd4b1a60fe0c727b09 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/xtensa')
| -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) |