FAILED: patch "[PATCH] um: mm: check more comprehensively for stub changes" failed to apply to 4.19-stable tree
From: <gregkh@linuxfoundation.org>
Date: 2021-03-01 13:38:45
Subsystem:
the rest, user-mode linux (uml) · Maintainers:
Linus Torvalds, Richard Weinberger, Anton Ivanov, Johannes Berg
The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to [off-list ref].
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 47da29763ec9a153b9b685bff9db659e4e09e494 Mon Sep 17 00:00:00 2001
From: Johannes Berg <redacted>
Date: Wed, 13 Jan 2021 22:08:02 +0100
Subject: [PATCH] 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 <redacted>
Signed-off-by: Richard Weinberger <richard@nod.at>
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;