From c1a214ad82d7ac6f19fe48f90b13403b40ead9dc Mon Sep 17 00:00:00 2001 From: John Hubbard Date: Thu, 23 Aug 2018 09:16:58 +0300 Subject: [PATCH] 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 98e70866aacb ("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: 98e70866aacb ("mei: add support for variable length mei headers.") CC: Arnd Bergmann CC: Greg Kroah-Hartman Signed-off-by: John Hubbard Signed-off-by: Tomas Winkler Signed-off-by: Greg Kroah-Hartman --- drivers/misc/mei/client.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/misc/mei/client.c b/drivers/misc/mei/client.c index 4ab6251d418e..ebdcf0b450e2 100644 --- a/drivers/misc/mei/client.c +++ b/drivers/misc/mei/client.c @@ -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); -- 2.30.2