From: Vasily Averin vvs@virtuozzo.com
[ 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@virtuozzo.com Reviewed-by: Cornelia Huck cohuck@redhat.com Signed-off-by: Christian Borntraeger borntraeger@de.ibm.com Signed-off-by: Vasily Averin vvs@virtuozzo.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 9082476b51db9..4e9f794176d35 100644 --- a/drivers/s390/cio/blacklist.c +++ b/drivers/s390/cio/blacklist.c @@ -302,8 +302,10 @@ 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) { @@ -313,7 +315,6 @@ cio_ignore_proc_seq_next(struct seq_file *s, void *it, loff_t *offset) return NULL; } else iter->devno++; - (*offset)++; return iter; }