From: Vasily Averin <vvs@xxxxxxxxxxxxx> [ Upstream commit 8b101a5e14f2161869636ff9cb4907b7749dc0c2 ] if seq_file .next fuction does not change position index, read after some lseek can generate unexpected output. Link: https://bugzilla.kernel.org/show_bug.cgi?id=206283 Link: https://lore.kernel.org/r/d44c53a7-9bc1-15c7-6d4a-0c10cb9dffce@xxxxxxxxxxxxx Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx> Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/s390/cio/blacklist.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/s390/cio/blacklist.c b/drivers/s390/cio/blacklist.c index 20314aad7ab7d..f329459cadf14 100644 --- a/drivers/s390/cio/blacklist.c +++ b/drivers/s390/cio/blacklist.c @@ -303,8 +303,10 @@ static void * cio_ignore_proc_seq_next(struct seq_file *s, void *it, loff_t *offset) { struct ccwdev_iter *iter; + loff_t p = *offset; - if (*offset >= (__MAX_SUBCHANNEL + 1) * (__MAX_SSID + 1)) + (*offset)++; + if (p >= (__MAX_SUBCHANNEL + 1) * (__MAX_SSID + 1)) return NULL; iter = it; if (iter->devno == __MAX_SUBCHANNEL) { @@ -314,7 +316,6 @@ cio_ignore_proc_seq_next(struct seq_file *s, void *it, loff_t *offset) return NULL; } else iter->devno++; - (*offset)++; return iter; } -- 2.20.1
