USB: ldusb: fix read info leaks
commit 7a6f22d7 upstream. Fix broken read implementation, which could be used to trigger slab info leaks. The driver failed to check if the custom ring buffer was still empty when waking up after having waited for more data. This would happen on every interrupt-in completion, even if no data had been added to the ring buffer (e.g. on disconnect events). Due to missing sanity checks and uninitialised (kmalloced) ring-buffer entries, this meant that huge slab info leaks could easily be triggered. Note that the empty-buffer check after wakeup is enough to fix the info leak on disconnect, but let's clear the buffer on allocation and add a sanity check to read() to prevent further leaks. Fixes: 2824bd25 ("[PATCH] USB: add ldusb driver") Cc: stable <stable@vger.kernel.org> # 2.6.13 Reported-by: syzbot+6fe95b826644f7f12b0b@syzkaller.appspotmail.com Signed-off-by: Johan Hovold <johan@kernel.org> Link: https://lore.kernel.org/r/20191018151955.25135-2-johan@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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