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mei: fix use-after-free in mei_cl_write 

KASAN reports a use-after-free during startup, in mei_cl_write:

    BUG: KASAN: use-after-free in mei_cl_write+0x601/0x870 [mei]
       (drivers/misc/mei/client.c:1770)

This is caused by commit 98e70866aa ("mei: add support for variable
length mei headers."), which changed the return value from len, to
buf->size. That ends up using a stale buf pointer, because blocking
call, the cb (callback) is deleted in me_cl_complete() function.

However, fortunately, len remains unchanged throughout the function
(and I don't see anything else that would require re-reading buf->size
either), so the fix is to simply revert the change, and return len, as
before.

Fixes: 98e70866aa ("mei: add support for variable length mei headers.")
CC: Arnd Bergmann <arnd@arndb.de>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
John Hubbard 2018-08-23 09:16:58 +03:00 committed by Greg Kroah-Hartman
parent 8d2d8935d3
commit c1a214ad82
1 changed files with 1 additions and 1 deletions
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2
drivers/misc/mei/client.c
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@ -1767,7 +1767,7 @@ out:
}
}
rets = buf->size;
rets = len;
err:
cl_dbg(dev, cl, "rpm: autosuspend\n");
pm_runtime_mark_last_busy(dev->dev);