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| author | Johannes Berg <johannes.berg@intel.com> | 2021-01-14 00:08:02 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-03-04 12:26:50 +0300 |
| commit | 5b5d76028056db3296a2c9b997dad13c5bec78b5 (patch) | |
| tree | 58b5a183d0fe55130117cbd21de0657e8e003f08 /arch/um | |
| parent | b95baf4efb6835d4a76d5db5b74bad84f234a872 (diff) | |
| download | linux-5b5d76028056db3296a2c9b997dad13c5bec78b5.tar.xz | |
um: mm: check more comprehensively for stub changes
commit 47da29763ec9a153b9b685bff9db659e4e09e494 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/um')
| -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 b7eaf655635c..11499136720d 100644 --- a/arch/um/kernel/tlb.c +++ b/arch/um/kernel/tlb.c @@ -126,6 +126,9 @@ 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 @@ -163,7 +166,7 @@ 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) { @@ -193,6 +196,9 @@ 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) && @@ -433,6 +439,10 @@ 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; |