On Tue, Dec 17, 2019 at 01:28:29PM +0900, Nobuhiro Iwamatsu wrote:
On Mon, Dec 16, 2019 at 06:48:50PM +0100, Greg Kroah-Hartman wrote:
From: Ming Lei ming.lei@redhat.com
commit 8962842ca5abdcf98e22ab3b2b45a103f0408b95 upstream.
It is reported that sysfs buffer overflow can be triggered if the system has too many CPU cores(>841 on 4K PAGE_SIZE) when showing CPUs of hctx via /sys/block/$DEV/mq/$N/cpu_list.
Use snprintf to avoid the potential buffer overflow.
This version doesn't change the attribute format, and simply stops showing CPU numbers if the buffer is going to overflow.
Cc: stable@vger.kernel.org Fixes: 676141e48af7("blk-mq: don't dump CPU -> hw queue map on driver load") Signed-off-by: Ming Lei ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
This commit also required following commit:
commit d2c9be89f8ebe7ebcc97676ac40f8dec1cf9b43a Author: Ming Lei ming.lei@redhat.com Date: Mon Nov 4 16:26:53 2019 +0800
blk-mq: make sure that line break can be printed 8962842ca5ab ("blk-mq: avoid sysfs buffer overflow with too many CPU cores") avoids sysfs buffer overflow, and reserves one character for line break. However, the last snprintf() doesn't get correct 'size' parameter passed in, so fixed it. Fixes: 8962842ca5ab ("blk-mq: avoid sysfs buffer overflow with too many CPU cores") Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>And this is also required for 4.4, 4.9 and 4.19. Please apply.
Thank you for catching this, now queued up.
greg k-h