From: Oleg Nesterov <o...@redhat.com>
commit 013b2deba9a6b80ca02f4fafd7dedf875e9b4450 upstream.
uprobe_write_opcode() must not cross page boundary; prepare_uprobe()
relies on arch_uprobe_analyze_insn() which should validate "vaddr" but
some architectures (csky, s390, and sparc) don't do this.
We can remove the BUG_ON() check in prepare_uprobe() and validate the
offset early in __uprobe_register(). The new IS_ALIGNED() check matches
the alignment check in arch_prepare_kprobe() on supported architectures,
so I think that all insns must be aligned to UPROBE_SWBP_INSN_SIZE.
Another problem is __update_ref_ctr() which was wrong from the very
beginning, it can read/write outside of kmap'ed page unless "vaddr" is
aligned to sizeof(short), __uprobe_register() should check this too.
Reported-by: Linus Torvalds <torva...@linux-foundation.org>
Suggested-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Oleg Nesterov <o...@redhat.com>
Reviewed-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntrae...@de.ibm.com>
Tested-by: Sven Schnelle <sv...@linux.ibm.com>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: sta...@vger.kernel.org
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
kernel/events/uprobes.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -612,10 +612,6 @@ static int prepare_uprobe(struct uprobe
if (ret)
goto out;
- /* uprobe_write_opcode() assumes we don't cross page boundary */
- BUG_ON((uprobe->offset & ~PAGE_MASK) +
- UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);
-
smp_wmb(); /* pairs with the smp_rmb() in handle_swbp() */
set_bit(UPROBE_COPY_INSN, &uprobe->flags);
@@ -894,6 +890,15 @@ int uprobe_register(struct inode *inode,
if (offset > i_size_read(inode))
return -EINVAL;
+ /*
+ * This ensures that copy_from_page(), copy_to_page() and
+ * __update_ref_ctr() can't cross page boundary.
+ */
+ if (!IS_ALIGNED(offset, UPROBE_SWBP_INSN_SIZE))
+ return -EINVAL;
+ if (!IS_ALIGNED(ref_ctr_offset, sizeof(short)))
+ return -EINVAL;
+
retry:
uprobe = alloc_uprobe(inode, offset);
if (!uprobe)
@@ -1704,6 +1709,9 @@ static int is_trap_at_addr(struct mm_str
uprobe_opcode_t opcode;
int result;
+ if (WARN_ON_ONCE(!IS_ALIGNED(vaddr, UPROBE_SWBP_INSN_SIZE)))
+ return -EINVAL;
+
pagefault_disable();
result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr);
pagefault_enable();
