llc: fix skb UAF and leaks on llc_mac_hdr_init() failure

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In llc_conn_ac_resend_i_xxx_x_set_0_or_send_rr(), if llc_mac_hdr_init()
fails, kfree_skb(skb) is called instead of kfree_skb(nskb). This leaks
the newly allocated nskb, reads from the freed skb via LLC_I_GET_NR(pdu),
and double-frees skb when llc_conn_state_process() drops its reference.

In llc_sap_action_send_xid_r() and llc_sap_action_send_test_r(), nskb is
leaked if llc_mac_hdr_init() returns an error.

Free nskb in all three error paths.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Closes: https://lore.kernel.org/netdev/179022851638.2160803.1808206741379444999@kernel.org/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260924082951.1599377-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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Eric Dumazet 2026-09-24 08:29:48 +00:00 • committed by Jakub Kicinski

parent 72b5b9a28b

commit 72f9dd522f

2 changed files with 5 additions and 1 deletions

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net/llc/llc_c_ac.c

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4

net/llc/llc_s_ac.c

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