diff options
| author | Ming Lei <ming.lei@redhat.com> | 2019-11-02 16:02:15 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-11-02 08:02:21 -0600 |
| commit | 8962842ca5abdcf98e22ab3b2b45a103f0408b95 (patch) | |
| tree | 8c2587331bbd6da0d4a520af10c30a23b2a55f63 | |
| parent | 626fb735a43ddcb7b2c58c27cb03b098acc03339 (diff) | |
blk-mq: avoid sysfs buffer overflow with too many CPU cores
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>
| -rw-r--r-- | block/blk-mq-sysfs.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c index 81a273b43329..4caa56d1bc85 100644 --- a/block/blk-mq-sysfs.c +++ b/block/blk-mq-sysfs.c @@ -158,20 +158,25 @@ static ssize_t blk_mq_hw_sysfs_nr_reserved_tags_show(struct blk_mq_hw_ctx *hctx, static ssize_t blk_mq_hw_sysfs_cpus_show(struct blk_mq_hw_ctx *hctx, char *page) { + const size_t size = PAGE_SIZE - 1; unsigned int i, first = 1; - ssize_t ret = 0; + int ret = 0, pos = 0; for_each_cpu(i, hctx->cpumask) { if (first) - ret += sprintf(ret + page, "%u", i); + ret = snprintf(pos + page, size - pos, "%u", i); else - ret += sprintf(ret + page, ", %u", i); + ret = snprintf(pos + page, size - pos, ", %u", i); + + if (ret >= size - pos) + break; first = 0; + pos += ret; } - ret += sprintf(ret + page, "\n"); - return ret; + ret = snprintf(pos + page, size - pos, "\n"); + return pos + ret; } static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_nr_tags = { |