On Fri, Aug 16, 2019 at 11:42 AM Bart Van Assche bvanassche@acm.org wrote:
On 8/15/19 7:54 PM, Ming Lei wrote:
It is reported that sysfs buffer overflow can be triggered in case of too many CPU cores(>841 on 4K PAGE_SIZE) when showing CPUs in blk_mq_hw_sysfs_cpus_show().
So use cpumap_print_to_pagebuf() to print the info and fix the potential buffer overflow issue.
Cc: stable@vger.kernel.org Cc: Mark Ray mark.ray@hpe.com Cc: Greg KH gregkh@linuxfoundation.org Fixes: 676141e48af7("blk-mq: don't dump CPU -> hw queue map on driver load") Signed-off-by: Ming Lei ming.lei@redhat.com
block/blk-mq-sysfs.c | 15 +-------------- 1 file changed, 1 insertion(+), 14 deletions(-)
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c index d6e1a9bd7131..4d0d32377ba3 100644 --- a/block/blk-mq-sysfs.c +++ b/block/blk-mq-sysfs.c @@ -166,20 +166,7 @@ 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) {
unsigned int i, first = 1;ssize_t ret = 0;for_each_cpu(i, hctx->cpumask) {if (first)ret += sprintf(ret + page, "%u", i);elseret += sprintf(ret + page, ", %u", i);first = 0;}ret += sprintf(ret + page, "\n");return ret;
return cpumap_print_to_pagebuf(true, page, hctx->cpumask);}
static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_nr_tags = {
Although this patch looks fine to me, shouldn't this attribute be documented under Documentation/ABI/?
That is another problem, not closely related with this buffer-overflow issue.
I suggest to fix the buffer overflow first, which is triggered from userspace.
Thanks, Ming Lei