The patch below does not apply to the 5.7-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 65f0f017e7be8c70330372df23bcb2a407ecf02d Mon Sep 17 00:00:00 2001

From: Coly Li colyli@suse.de Date: Sat, 25 Jul 2020 20:00:21 +0800 Subject: [PATCH] bcache: avoid nr_stripes overflow in bcache_device_init()

For some block devices which large capacity (e.g. 8TB) but small io_opt size (e.g. 8 sectors), in bcache_device_init() the stripes number calcu- lated by, DIV_ROUND_UP_ULL(sectors, d->stripe_size); might be overflow to the unsigned int bcache_device->nr_stripes.

This patch uses the uint64_t variable to store DIV_ROUND_UP_ULL() and after the value is checked to be available in unsigned int range, sets it to bache_device->nr_stripes. Then the overflow is avoided.

Reported-and-tested-by: Ken Raeburn raeburn@redhat.com Signed-off-by: Coly Li colyli@suse.de Cc: stable@vger.kernel.org Link: https://bugzilla.redhat.com/show_bug.cgi?id=1783075 Signed-off-by: Jens Axboe axboe@kernel.dk

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index 4a77bfd4009f..0f90616dc8d3 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -835,19 +835,19 @@ static int bcache_device_init(struct bcache_device *d, unsigned int block_size, struct request_queue *q; const size_t max_stripes = min_t(size_t, INT_MAX, SIZE_MAX / sizeof(atomic_t)); - size_t n; + uint64_t n; int idx;

if (!d->stripe_size) d->stripe_size = 1 << 31;

- d->nr_stripes = DIV_ROUND_UP_ULL(sectors, d->stripe_size); - - if (!d->nr_stripes || d->nr_stripes > max_stripes) { - pr_err("nr_stripes too large or invalid: %u (start sector beyond end of disk?)\n", - (unsigned int)d->nr_stripes); + n = DIV_ROUND_UP_ULL(sectors, d->stripe_size); + if (!n || n > max_stripes) { + pr_err("nr_stripes too large or invalid: %llu (start sector beyond end of disk?)\n", + n); return -ENOMEM; } + d->nr_stripes = n;

n = d->nr_stripes * sizeof(atomic_t); d->stripe_sectors_dirty = kvzalloc(n, GFP_KERNEL);