| From 08791c9c3bc83d095cd0836a27b1f7b5aea1413e Mon Sep 17 00:00:00 2001 |
| From: Coly Li <colyli@suse.de> |
| Date: Sat, 25 Jul 2020 20:00:22 +0800 |
| Subject: [PATCH] bcache: fix overflow in offset_to_stripe() |
| |
| commit 7a1481267999c02abf4a624515c1b5c7c1fccbd6 upstream. |
| |
| offset_to_stripe() returns the stripe number (in type unsigned int) from |
| an offset (in type uint64_t) by the following calculation, |
| do_div(offset, d->stripe_size); |
| For large capacity backing device (e.g. 18TB) with small stripe size |
| (e.g. 4KB), the result is 4831838208 and exceeds UINT_MAX. The actual |
| returned value which caller receives is 536870912, due to the overflow. |
| |
| Indeed in bcache_device_init(), bcache_device->nr_stripes is limited in |
| range [1, INT_MAX]. Therefore all valid stripe numbers in bcache are |
| in range [0, bcache_dev->nr_stripes - 1]. |
| |
| This patch adds a upper limition check in offset_to_stripe(): the max |
| valid stripe number should be less than bcache_device->nr_stripes. If |
| the calculated stripe number from do_div() is equal to or larger than |
| bcache_device->nr_stripe, -EINVAL will be returned. (Normally nr_stripes |
| is less than INT_MAX, exceeding upper limitation doesn't mean overflow, |
| therefore -EOVERFLOW is not used as error code.) |
| |
| This patch also changes nr_stripes' type of struct bcache_device from |
| 'unsigned int' to 'int', and return value type of offset_to_stripe() |
| from 'unsigned int' to 'int', to match their exact data ranges. |
| |
| All locations where bcache_device->nr_stripes and offset_to_stripe() are |
| referenced also get updated for the above type change. |
| |
| 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> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h |
| index eb918b2dc805..2e396954b39d 100644 |
| --- a/drivers/md/bcache/bcache.h |
| +++ b/drivers/md/bcache/bcache.h |
| @@ -264,7 +264,7 @@ struct bcache_device { |
| #define BCACHE_DEV_UNLINK_DONE 2 |
| #define BCACHE_DEV_WB_RUNNING 3 |
| #define BCACHE_DEV_RATE_DW_RUNNING 4 |
| - unsigned int nr_stripes; |
| + int nr_stripes; |
| unsigned int stripe_size; |
| atomic_t *stripe_sectors_dirty; |
| unsigned long *full_dirty_stripes; |
| diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c |
| index e9ffcea1ca50..58bedd51e11b 100644 |
| --- a/drivers/md/bcache/writeback.c |
| +++ b/drivers/md/bcache/writeback.c |
| @@ -516,15 +516,19 @@ void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned int inode, |
| uint64_t offset, int nr_sectors) |
| { |
| struct bcache_device *d = c->devices[inode]; |
| - unsigned int stripe_offset, stripe, sectors_dirty; |
| + unsigned int stripe_offset, sectors_dirty; |
| + int stripe; |
| |
| if (!d) |
| return; |
| |
| + stripe = offset_to_stripe(d, offset); |
| + if (stripe < 0) |
| + return; |
| + |
| if (UUID_FLASH_ONLY(&c->uuids[inode])) |
| atomic_long_add(nr_sectors, &c->flash_dev_dirty_sectors); |
| |
| - stripe = offset_to_stripe(d, offset); |
| stripe_offset = offset & (d->stripe_size - 1); |
| |
| while (nr_sectors) { |
| @@ -564,12 +568,12 @@ static bool dirty_pred(struct keybuf *buf, struct bkey *k) |
| static void refill_full_stripes(struct cached_dev *dc) |
| { |
| struct keybuf *buf = &dc->writeback_keys; |
| - unsigned int start_stripe, stripe, next_stripe; |
| + unsigned int start_stripe, next_stripe; |
| + int stripe; |
| bool wrapped = false; |
| |
| stripe = offset_to_stripe(&dc->disk, KEY_OFFSET(&buf->last_scanned)); |
| - |
| - if (stripe >= dc->disk.nr_stripes) |
| + if (stripe < 0) |
| stripe = 0; |
| |
| start_stripe = stripe; |
| diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h |
| index 4e4c6810dc3c..c4ff76037227 100644 |
| --- a/drivers/md/bcache/writeback.h |
| +++ b/drivers/md/bcache/writeback.h |
| @@ -33,10 +33,22 @@ static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d) |
| return ret; |
| } |
| |
| -static inline unsigned int offset_to_stripe(struct bcache_device *d, |
| +static inline int offset_to_stripe(struct bcache_device *d, |
| uint64_t offset) |
| { |
| do_div(offset, d->stripe_size); |
| + |
| + /* d->nr_stripes is in range [1, INT_MAX] */ |
| + if (unlikely(offset >= d->nr_stripes)) { |
| + pr_err("Invalid stripe %llu (>= nr_stripes %d).\n", |
| + offset, d->nr_stripes); |
| + return -EINVAL; |
| + } |
| + |
| + /* |
| + * Here offset is definitly smaller than INT_MAX, |
| + * return it as int will never overflow. |
| + */ |
| return offset; |
| } |
| |
| @@ -44,7 +56,10 @@ static inline bool bcache_dev_stripe_dirty(struct cached_dev *dc, |
| uint64_t offset, |
| unsigned int nr_sectors) |
| { |
| - unsigned int stripe = offset_to_stripe(&dc->disk, offset); |
| + int stripe = offset_to_stripe(&dc->disk, offset); |
| + |
| + if (stripe < 0) |
| + return false; |
| |
| while (1) { |
| if (atomic_read(dc->disk.stripe_sectors_dirty + stripe)) |
| -- |
| 2.27.0 |
| |