b7a679ba7c
Christoph reported a possible deadlock while the TCP stack
destroys an unaccepted subflow due to an incoming reset: the
MPTCP socket error path tries to acquire the msk-level socket
lock while TCP still owns the listener socket accept queue
spinlock, and the reverse dependency already exists in the
TCP stack.
Note that the above is actually a lockdep false positive, as
the chain involves two separate sockets. A different per-socket
lockdep key will address the issue, but such a change will be
quite invasive.
Instead, we can simply stop earlier the socket error handling
for orphaned or unaccepted subflows, breaking the critical
lockdep chain. Error handling in such a scenario is a no-op.
Reported-and-tested-by: Christoph Paasch <cpaasch@apple.com>
Fixes:
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.. | ||
bpf.c | ||
crypto_test.c | ||
crypto.c | ||
ctrl.c | ||
diag.c | ||
fastopen.c | ||
Kconfig | ||
Makefile | ||
mib.c | ||
mib.h | ||
mptcp_diag.c | ||
options.c | ||
pm_netlink.c | ||
pm_userspace.c | ||
pm.c | ||
protocol.c | ||
protocol.h | ||
sockopt.c | ||
subflow.c | ||
syncookies.c | ||
token_test.c | ||
token.c |