diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2015-07-21 15:40:31 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-07-31 10:38:06 +0200 |
| commit | f58bea2fec63db72f8050ade709358257e9102ab (patch) | |
| tree | 1df4b2f3221a1a390282e2dfe6b752da611fb7a8 /kernel/events | |
| parent | db087ef69a2b155ae001665bf0b3806abde7ee34 (diff) | |
uprobes: Fix the usage of install_special_mapping()
install_special_mapping(pages) expects that "pages" is the zero-
terminated array while xol_add_vma() passes &area->page, this
means that special_mapping_fault() can wrongly use the next
member in xol_area (vaddr) as "struct page *".
Fortunately, this area is not expandable so pgoff != 0 isn't
possible (modulo bugs in special_mapping_vmops), but still this
does not look good.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134031.GA4789@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/uprobes.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 0f370ef57a02..4b8ac5f13320 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -99,7 +99,7 @@ struct xol_area { wait_queue_head_t wq; /* if all slots are busy */ atomic_t slot_count; /* number of in-use slots */ unsigned long *bitmap; /* 0 = free slot */ - struct page *page; + struct page *pages[2]; /* * We keep the vma's vm_start rather than a pointer to the vma @@ -1142,7 +1142,7 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) } ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE, - VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page); + VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, area->pages); if (ret) goto fail; @@ -1168,21 +1168,22 @@ static struct xol_area *__create_xol_area(unsigned long vaddr) if (!area->bitmap) goto free_area; - area->page = alloc_page(GFP_HIGHUSER); - if (!area->page) + area->pages[0] = alloc_page(GFP_HIGHUSER); + if (!area->pages[0]) goto free_bitmap; + area->pages[1] = NULL; area->vaddr = vaddr; init_waitqueue_head(&area->wq); /* Reserve the 1st slot for get_trampoline_vaddr() */ set_bit(0, area->bitmap); atomic_set(&area->slot_count, 1); - copy_to_page(area->page, 0, &insn, UPROBE_SWBP_INSN_SIZE); + copy_to_page(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE); if (!xol_add_vma(mm, area)) return area; - __free_page(area->page); + __free_page(area->pages[0]); free_bitmap: kfree(area->bitmap); free_area: @@ -1220,7 +1221,7 @@ void uprobe_clear_state(struct mm_struct *mm) if (!area) return; - put_page(area->page); + put_page(area->pages[0]); kfree(area->bitmap); kfree(area); } @@ -1289,7 +1290,7 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe) if (unlikely(!xol_vaddr)) return 0; - arch_uprobe_copy_ixol(area->page, xol_vaddr, + arch_uprobe_copy_ixol(area->pages[0], xol_vaddr, &uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); return xol_vaddr; |