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| author | Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> | 2019-05-13 20:28:00 +0300 |
|---|---|---|
| committer | Vineet Gupta <vgupta@synopsys.com> | 2019-05-20 20:09:10 +0300 |
| commit | a8c715b4dd73c26a81a9cc8dc792aa715d8b4bb2 (patch) | |
| tree | 6155b49813d31180e7f53afa91d3011eee978d7b /arch/arc | |
| parent | 89c92142f75eb80064f5b9f1111484b1b4d81790 (diff) | |
| download | linux-a8c715b4dd73c26a81a9cc8dc792aa715d8b4bb2.tar.xz | |
ARC: mm: SIGSEGV userspace trying to access kernel virtual memory
As of today if userspace process tries to access a kernel virtual addres
(0x7000_0000 to 0x7ffff_ffff) such that a legit kernel mapping already
exists, that process hangs instead of being killed with SIGSEGV
Fix that by ensuring that do_page_fault() handles kenrel vaddr only if
in kernel mode.
And given this, we can also simplify the code a bit. Now a vmalloc fault
implies kernel mode so its failure (for some reason) can reuse the
@no_context label and we can remove @bad_area_nosemaphore.
Reproduce user test for original problem:
------------------------>8-----------------
#include <stdlib.h>
#include <stdint.h>
int main(int argc, char *argv[])
{
volatile uint32_t temp;
temp = *(uint32_t *)(0x70000000);
}
------------------------>8-----------------
Cc: <stable@vger.kernel.org>
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'arch/arc')
| -rw-r--r-- | arch/arc/mm/fault.c | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c index 8df1638259f3..6836095251ed 100644 --- a/arch/arc/mm/fault.c +++ b/arch/arc/mm/fault.c @@ -66,7 +66,7 @@ void do_page_fault(unsigned long address, struct pt_regs *regs) struct vm_area_struct *vma = NULL; struct task_struct *tsk = current; struct mm_struct *mm = tsk->mm; - int si_code = 0; + int si_code = SEGV_MAPERR; int ret; vm_fault_t fault; int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */ @@ -81,16 +81,14 @@ void do_page_fault(unsigned long address, struct pt_regs *regs) * only copy the information from the master page table, * nothing more. */ - if (address >= VMALLOC_START) { + if (address >= VMALLOC_START && !user_mode(regs)) { ret = handle_kernel_vaddr_fault(address); if (unlikely(ret)) - goto bad_area_nosemaphore; + goto no_context; else return; } - si_code = SEGV_MAPERR; - /* * If we're in an interrupt or have no user * context, we must not take the fault.. @@ -198,7 +196,6 @@ good_area: bad_area: up_read(&mm->mmap_sem); -bad_area_nosemaphore: /* User mode accesses just cause a SIGSEGV */ if (user_mode(regs)) { tsk->thread.fault_address = address; |