On 1/24/20 12:03 PM, Vasily Averin wrote:
On 1/24/20 1:03 PM, Daniel Borkmann wrote:
On 1/24/20 7:17 AM, Vasily Averin wrote:
if seq_file .next fuction does not change position index,
read after some lseek can generate unexpected output.
https://bugzilla.kernel.org/show_bug.cgi?id=206283
Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
---
kernel/bpf/inode.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index ecf42be..9008a20 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -196,6 +196,7 @@ static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos)
void *key = map_iter(m)->key;
void *prev_key;
+ (*pos)++;
if (map_iter(m)->done)
return NULL;
Hm, how did you test this change? Please elaborate, since in map_seq_next()
we do increment position index:
Position index should be updated even if .next returns NULL.
Sorry, I've not tested this case.
$ dd if=AFFECTED_FILE bs=1000 skip=1
With any huge bs it will generate last line.
If you'll specify bs in middle of last line --
dd will output rest of list line and then whole last line once again.
static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
struct bpf_map *map = seq_file_to_map(m);
void *key = map_iter(m)->key;
void *prev_key;
if (map_iter(m)->done)
return NULL;
if (unlikely(v == SEQ_START_TOKEN))
prev_key = NULL;
else
prev_key = key;
if (map->ops->map_get_next_key(map, prev_key, key)) {
map_iter(m)->done = true;
return NULL;
}
++(*pos); <------------ here
You are right, I've missed it, it should be removed.
Ok, please respin v2 then.
Thanks,
Daniel
