diff options
| author | Johannes Berg <johannes.berg@intel.com> | 2021-01-13 22:08:02 +0100 |
|---|---|---|
| committer | Richard Weinberger <richard@nod.at> | 2021-02-12 21:31:08 +0100 |
| commit | 47da29763ec9a153b9b685bff9db659e4e09e494 (patch) | |
| tree | 05481f2a307bd8f7b5ded345b24c196dbf883302 /arch/um/kernel | |
| parent | e1e22d0d9183aaaf65acf0cb529cb51ddbc12e08 (diff) | |
um: mm: check more comprehensively for stub changes
If userspace tries to change the stub, we need to kill it,
because otherwise it can escape the virtual machine. In a
few cases the stub checks weren't good, e.g. if userspace
just tries to
mmap(0x100000 - 0x1000, 0x3000, ...)
it could succeed to get a new private/anonymous mapping
replacing the stubs. Fix this by checking everywhere, and
checking for _overlap_, not just direct changes.
Cc: stable@vger.kernel.org
Fixes: 3963333fe676 ("uml: cover stubs with a VMA")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um/kernel')
| -rw-r--r-- | arch/um/kernel/tlb.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c index 61776790cd67..89468da6bf88 100644 --- a/arch/um/kernel/tlb.c +++ b/arch/um/kernel/tlb.c @@ -125,6 +125,9 @@ static int add_mmap(unsigned long virt, unsigned long phys, unsigned long len, struct host_vm_op *last; int fd = -1, ret = 0; + if (virt + len > STUB_START && virt < STUB_END) + return -EINVAL; + if (hvc->userspace) fd = phys_mapping(phys, &offset); else @@ -162,7 +165,7 @@ static int add_munmap(unsigned long addr, unsigned long len, struct host_vm_op *last; int ret = 0; - if ((addr >= STUB_START) && (addr < STUB_END)) + if (addr + len > STUB_START && addr < STUB_END) return -EINVAL; if (hvc->index != 0) { @@ -192,6 +195,9 @@ static int add_mprotect(unsigned long addr, unsigned long len, struct host_vm_op *last; int ret = 0; + if (addr + len > STUB_START && addr < STUB_END) + return -EINVAL; + if (hvc->index != 0) { last = &hvc->ops[hvc->index - 1]; if ((last->type == MPROTECT) && @@ -472,6 +478,10 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long address) struct mm_id *mm_id; address &= PAGE_MASK; + + if (address >= STUB_START && address < STUB_END) + goto kill; + pgd = pgd_offset(mm, address); if (!pgd_present(*pgd)) goto kill; |