net: gtp: Fix Use-After-Free in gtp_dellink

stable inclusion
from stable-v4.19.313
commit 07b20d0a3dc13fb1adff10b60021a4924498da58
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9O0MU
CVE: CVE-2024-27396

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=07b20d0a3dc1



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[ Upstream commit f2a904107ee2b647bb7794a1a82b67740d7c8a64 ]

Since call_rcu, which is called in the hlist_for_each_entry_rcu traversal
of gtp_dellink, is not part of the RCU read critical section, it
is possible that the RCU grace period will pass during the traversal and
the key will be free.

To prevent this, it should be changed to hlist_for_each_entry_safe.

Fixes: 94dc550a ("gtp: fix an use-after-free in ipv4_pdp_find()")
Signed-off-by: Hyunwoo Kim <v4bel@theori.io>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Pu Lehui <pulehui@huawei.com>