Messages in this thread Patch in this message | | | From | Tomas Winkler <> | Subject | [char-misc for 4.19] mei: fix use-after-free in mei_cl_write | Date | Thu, 23 Aug 2018 09:16:58 +0300 |
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From: John Hubbard <jhubbard@nvidia.com>
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 <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> --- V2: 1. Add better explaination in the commit message. 2. Add Fixes: marker
BTW: The usage len is changed in furhter patches that were not yet merged.
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 @@ ssize_t mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb) } } - rets = buf->size; + rets = len; err: cl_dbg(dev, cl, "rpm: autosuspend\n"); pm_runtime_mark_last_busy(dev->dev); -- 2.14.4
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