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ARC: mm: SIGSEGV userspace trying to access kernel virtual memory
[ Upstream commit a8c715b4dd
]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
7edfa9c99d
commit
cacbc85376
1 changed files with 3 additions and 6 deletions
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@ -66,7 +66,7 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
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struct vm_area_struct *vma = NULL;
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struct task_struct *tsk = current;
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struct mm_struct *mm = tsk->mm;
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int si_code = 0;
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int si_code = SEGV_MAPERR;
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int ret;
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vm_fault_t fault;
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int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */
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@ -81,16 +81,14 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
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* only copy the information from the master page table,
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* nothing more.
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*/
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if (address >= VMALLOC_START) {
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if (address >= VMALLOC_START && !user_mode(regs)) {
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ret = handle_kernel_vaddr_fault(address);
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if (unlikely(ret))
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goto bad_area_nosemaphore;
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goto no_context;
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else
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return;
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}
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si_code = SEGV_MAPERR;
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/*
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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@ -198,7 +196,6 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
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bad_area:
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up_read(&mm->mmap_sem);
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bad_area_nosemaphore:
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/* User mode accesses just cause a SIGSEGV */
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if (user_mode(regs)) {
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tsk->thread.fault_address = address;
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