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linux/net/tipc/socket.c
Mehul Rao 3bc9998041 tipc: fix divide-by-zero in tipc_sk_filter_connect() 
commit 6c5a9baa15 upstream.

A user can set conn_timeout to any value via
setsockopt(TIPC_CONN_TIMEOUT), including values less than 4.  When a
SYN is rejected with TIPC_ERR_OVERLOAD and the retry path in
tipc_sk_filter_connect() executes:

    delay %= (tsk->conn_timeout / 4);

If conn_timeout is in the range [0, 3], the integer division yields 0,
and the modulo operation triggers a divide-by-zero exception, causing a
kernel oops/panic.

Fix this by clamping conn_timeout to a minimum of 4 at the point of use
in tipc_sk_filter_connect().

Oops: divide error: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 119 Comm: poc-F144 Not tainted 7.0.0-rc2+
RIP: 0010:tipc_sk_filter_rcv (net/tipc/socket.c:2236 net/tipc/socket.c:2362)
Call Trace:
 tipc_sk_backlog_rcv (include/linux/instrumented.h:82 include/linux/atomic/atomic-instrumented.h:32 include/net/sock.h:2357 net/tipc/socket.c:2406)
 __release_sock (include/net/sock.h:1185 net/core/sock.c:3213)
 release_sock (net/core/sock.c:3797)
 tipc_connect (net/tipc/socket.c:2570)
 __sys_connect (include/linux/file.h:62 include/linux/file.h:83 net/socket.c:2098)

Fixes: 6787927475 ("tipc: buffer overflow handling in listener socket")
Cc: stable@vger.kernel.org
Signed-off-by: Mehul Rao <mehulrao@gmail.com>
Reviewed-by: Tung Nguyen <tung.quang.nguyen@est.tech>
Link: https://patch.msgid.link/20260310170730.28841-1-mehulrao@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-04-18 10:33:14 +02:00

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