USB: cdc-acm: fix write and resume race
authorJohan Hovold <jhovold@gmail.com>
Mon, 26 May 2014 17:23:37 +0000 (19:23 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 27 May 2014 22:04:09 +0000 (15:04 -0700)
commite144ed28bed10684f9aaec6325ed974d53f76110
treebac73dbef9647f9c5af0f1d852e1c89fe838c982
parent5a345c20c17d87099224a4be12e69e5bd7023dca
USB: cdc-acm: fix write and resume race

Fix race between write() and resume() due to improper locking that could
lead to writes being reordered.

Resume must be done atomically and susp_count be protected by the
write_lock in order to prevent racing with write(). This could otherwise
lead to writes being reordered if write() grabs the write_lock after
susp_count is decremented, but before the delayed urb is submitted.

Fixes: 11ea859d64b6 ("USB: additional power savings for cdc-acm devices
that support remote wakeup")

Cc: <stable@vger.kernel.org> # v2.6.27
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/class/cdc-acm.c