diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2024-09-29 16:42:58 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2024-10-07 09:28:45 +0200 |
| commit | c16e2fdd746c78f5b2ce3c2ab8a26a61b6ed09e5 (patch) | |
| tree | a55a14d258a9f1f88c31a21aeb2628f0d29e86c1 /kernel/events | |
| parent | c5356ab1db28cafc448a50c26ba84442237abb98 (diff) | |
uprobes: deny mremap(xol_vma)
kernel/events/uprobes.c assumes that xol_area->vaddr is always correct but
a malicious application can remap its "[uprobes]" vma to another adress to
confuse the kernel. Introduce xol_mremap() to make this impossible.
With this change utask->xol_vaddr in xol_free_insn_slot() can't be invalid,
we can turn the offset check into WARN_ON_ONCE(offset >= PAGE_SIZE).
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240929144258.GA9492@redhat.com
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/uprobes.c | 30 |
1 files changed, 17 insertions, 13 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index c9f1e1e56b15..d3538b6c0831 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1472,9 +1472,15 @@ static vm_fault_t xol_fault(const struct vm_special_mapping *sm, return 0; } +static int xol_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma) +{ + return -EPERM; +} + static const struct vm_special_mapping xol_mapping = { .name = "[uprobes]", .fault = xol_fault, + .mremap = xol_mremap, }; /* Slot allocation for XOL */ @@ -1667,21 +1673,19 @@ static void xol_free_insn_slot(struct uprobe_task *utask) { struct xol_area *area = current->mm->uprobes_state.xol_area; unsigned long offset = utask->xol_vaddr - area->vaddr; + unsigned int slot_nr; utask->xol_vaddr = 0; - /* - * xol_vaddr must fit into [area->vaddr, area->vaddr + PAGE_SIZE). - * This check can only fail if the "[uprobes]" vma was mremap'ed. - */ - if (offset < PAGE_SIZE) { - int slot_nr = offset / UPROBE_XOL_SLOT_BYTES; - - clear_bit(slot_nr, area->bitmap); - atomic_dec(&area->slot_count); - smp_mb__after_atomic(); /* pairs with prepare_to_wait() */ - if (waitqueue_active(&area->wq)) - wake_up(&area->wq); - } + /* xol_vaddr must fit into [area->vaddr, area->vaddr + PAGE_SIZE) */ + if (WARN_ON_ONCE(offset >= PAGE_SIZE)) + return; + + slot_nr = offset / UPROBE_XOL_SLOT_BYTES; + clear_bit(slot_nr, area->bitmap); + atomic_dec(&area->slot_count); + smp_mb__after_atomic(); /* pairs with prepare_to_wait() */ + if (waitqueue_active(&area->wq)) + wake_up(&area->wq); } void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, |