Commit 623c8d5c authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'netdev-seq_file-next-functions-should-increase-position-index'

Vasily Averin says:

====================
netdev: seq_file .next functions should increase position index

In Aug 2018 NeilBrown noticed
commit 1f4aace6 ("fs/seq_file.c: simplify seq_file iteration code and interface")
"Some ->next functions do not increment *pos when they return NULL...
Note that such ->next functions are buggy and should be fixed.
A simple demonstration is

dd if=/proc/swaps bs=1000 skip=1

Choose any block size larger than the size of /proc/swaps.  This will
always show the whole last line of /proc/swaps"

Described problem is still actual. If you make lseek into middle of last output line
following read will output end of last line and whole last line once again.

$ dd if=/proc/swaps bs=1  # usual output
Filename				Type		Size	Used	Priority
/dev/dm-0                               partition	4194812	97536	-2
104+0 records in
104+0 records out
104 bytes copied

$ dd if=/proc/swaps bs=40 skip=1    # last line was generated twice
dd: /proc/swaps: cannot skip to specified offset
v/dm-0                               partition	4194812	97536	-2
/dev/dm-0                               partition	4194812	97536	-2
3+1 records in
3+1 records out
131 bytes copied

There are lot of other affected files, I've found 30+ including
/proc/net/ip_tables_matches and /proc/sysvipc/*

This patch-set fixes files related to netdev@

https://bugzilla.kernel.org/show_bug.cgi?id=206283


====================
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 2bec445f 4fc427e0
......@@ -70,8 +70,7 @@ static void *seq_tab_start(struct seq_file *seq, loff_t *pos)
static void *seq_tab_next(struct seq_file *seq, void *v, loff_t *pos)
{
v = seq_tab_get_idx(seq->private, *pos + 1);
if (v)
++*pos;
++(*pos);
return v;
}
......
......@@ -678,8 +678,7 @@ static void *l2t_seq_start(struct seq_file *seq, loff_t *pos)
static void *l2t_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
v = l2t_get_idx(seq, *pos);
if (v)
++*pos;
++(*pos);
return v;
}
......
......@@ -134,8 +134,7 @@ static void vcc_seq_stop(struct seq_file *seq, void *v)
static void *vcc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
v = vcc_walk(seq, 1);
if (v)
(*pos)++;
(*pos)++;
return v;
}
......
......@@ -3290,6 +3290,7 @@ static void *neigh_stat_seq_next(struct seq_file *seq, void *v, loff_t *pos)
*pos = cpu+1;
return per_cpu_ptr(tbl->stats, cpu);
}
(*pos)++;
return NULL;
}
......
......@@ -271,6 +271,7 @@ static void *rt_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
*pos = cpu+1;
return &per_cpu(rt_cache_stat, cpu);
}
(*pos)++;
return NULL;
}
......
......@@ -2495,14 +2495,13 @@ static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
struct net *net = seq_file_net(seq);
struct ipv6_route_iter *iter = seq->private;
++(*pos);
if (!v)
goto iter_table;
n = rcu_dereference_bh(((struct fib6_info *)v)->fib6_next);
if (n) {
++*pos;
if (n)
return n;
}
iter_table:
ipv6_route_check_sernum(iter);
......@@ -2510,8 +2509,6 @@ iter_table:
r = fib6_walk_continue(&iter->w);
spin_unlock_bh(&iter->tbl->tb6_lock);
if (r > 0) {
if (v)
++*pos;
return iter->w.leaf;
} else if (r < 0) {
fib6_walker_unlink(net, &iter->w);
......
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