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blk-mq: avoid sysfs buffer overflow with too many CPU cores
commit 8962842ca5
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 is contained in:
parent
51fb33d0b2
commit
365874a0ea
1 changed files with 10 additions and 5 deletions
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@ -145,20 +145,25 @@ static ssize_t blk_mq_hw_sysfs_nr_reserved_tags_show(struct blk_mq_hw_ctx *hctx,
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static ssize_t blk_mq_hw_sysfs_cpus_show(struct blk_mq_hw_ctx *hctx, char *page)
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{
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const size_t size = PAGE_SIZE - 1;
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unsigned int i, first = 1;
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ssize_t ret = 0;
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int ret = 0, pos = 0;
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for_each_cpu(i, hctx->cpumask) {
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if (first)
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ret += sprintf(ret + page, "%u", i);
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ret = snprintf(pos + page, size - pos, "%u", i);
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else
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ret += sprintf(ret + page, ", %u", i);
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ret = snprintf(pos + page, size - pos, ", %u", i);
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if (ret >= size - pos)
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break;
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first = 0;
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pos += ret;
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}
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ret += sprintf(ret + page, "\n");
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return ret;
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ret = snprintf(pos + page, size - pos, "\n");
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return pos + ret;
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}
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static struct attribute *default_ctx_attrs[] = {
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