From: Eric Dumazet Date: Wed, 18 Jun 2025 14:08:44 +0000 (+0000) Subject: net: atm: fix /proc/net/atm/lec handling X-Git-Tag: v6.16-rc3~27^2~3^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d03b79f459c7935cff830d98373474f440bd03ae;p=thirdparty%2Flinux.git net: atm: fix /proc/net/atm/lec handling /proc/net/atm/lec must ensure safety against dev_lec[] changes. It appears it had dev_put() calls without prior dev_hold(), leading to imbalance and UAF. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet Acked-by: Francois Romieu # Minor atm contributor Link: https://patch.msgid.link/20250618140844.1686882-3-edumazet@google.com Signed-off-by: Jakub Kicinski --- diff --git a/net/atm/lec.c b/net/atm/lec.c index 1e1f3eb0e2ba3..afb8d3eb21850 100644 --- a/net/atm/lec.c +++ b/net/atm/lec.c @@ -909,7 +909,6 @@ static void *lec_itf_walk(struct lec_state *state, loff_t *l) v = (dev && netdev_priv(dev)) ? lec_priv_walk(state, l, netdev_priv(dev)) : NULL; if (!v && dev) { - dev_put(dev); /* Partial state reset for the next time we get called */ dev = NULL; } @@ -933,6 +932,7 @@ static void *lec_seq_start(struct seq_file *seq, loff_t *pos) { struct lec_state *state = seq->private; + mutex_lock(&lec_mutex); state->itf = 0; state->dev = NULL; state->locked = NULL; @@ -950,8 +950,9 @@ static void lec_seq_stop(struct seq_file *seq, void *v) if (state->dev) { spin_unlock_irqrestore(&state->locked->lec_arp_lock, state->flags); - dev_put(state->dev); + state->dev = NULL; } + mutex_unlock(&lec_mutex); } static void *lec_seq_next(struct seq_file *seq, void *v, loff_t *pos)