5.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit d03b79f459c7935cff830d98373474f440bd03ae ]
/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 edumazet@google.com Acked-by: Francois Romieu romieu@fr.zoreil.com # Minor atm contributor Link: https://patch.msgid.link/20250618140844.1686882-3-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/atm/lec.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/atm/lec.c b/net/atm/lec.c index 5b9220c42dfcc..49fe366c3b1d7 100644 --- a/net/atm/lec.c +++ b/net/atm/lec.c @@ -916,7 +916,6 @@ 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; } @@ -940,6 +939,7 @@ 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; @@ -957,8 +957,9 @@ 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)