Commit-ID: f58bea2fec63db72f8050ade709358257e9102ab
Gitweb: http://git.kernel.org/tip/f58bea2fec63db72f8050ade709358257e9102ab
Author: Oleg Nesterov <oleg@xxxxxxxxxx>
AuthorDate: Tue, 21 Jul 2015 15:40:31 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 31 Jul 2015 10:38:06 +0200
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@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Pratyush Anand <panand@xxxxxxxxxx>
Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20150721134031.GA4789@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/events/uprobes.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 0f370ef..4b8ac5f 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;
--
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