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| author | Oleg Nesterov <oleg@redhat.com> | 2012-06-15 17:43:28 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2012-06-16 09:10:42 +0200 |
| commit | 5323ce71e4b4e1f188ebbc0cc7776885ea6c75fb (patch) | |
| tree | fd4f1445cd71a2a2cc0096f08a216e27bc3fc237 /Makefile | |
| parent | uprobes: __copy_insn() should ensure a_ops->readpage != NULL (diff) | |
| download | linux-5323ce71e4b4e1f188ebbc0cc7776885ea6c75fb.tar.xz linux-5323ce71e4b4e1f188ebbc0cc7776885ea6c75fb.zip | |
uprobes: Write_opcode()->__replace_page() can race with try_to_unmap()
write_opcode() gets old_page via get_user_pages() and then calls
__replace_page() which assumes that this old_page is still
mapped after pte_offset_map_lock().
This is not true if this old_page was already try_to_unmap()'ed,
and in this case everything __replace_page() does with old_page
is wrong. Just for example, put_page() is not balanced.
I think it is possible to teach __replace_page() to handle this
unlikely case correctly, but this patch simply changes it to use
page_check_address() and return -EAGAIN if it fails. The caller
should notice this error code and retry.
Note: write_opcode() asks for the cleanups, I'll try to do this
in a separate patch.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anton Arapov <anton@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120615154328.GA9571@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Makefile')
0 files changed, 0 insertions, 0 deletions