5.4-stable review patch. If anyone has any objections, please let me know.
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From: Yu-Chun Lin eleanor15x@gmail.com
[ Upstream commit 606572eb22c1786a3957d24307f5760bb058ca19 ]
According to the C11 standard (ISO/IEC 9899:2011, 6.5.7): "If E1 has a signed type and E1 x 2^E2 is not representable in the result type, the behavior is undefined."
Shifting 1 << 31 causes signed integer overflow, which leads to undefined behavior.
Fix this by explicitly using '1U << 31' to ensure the shift operates on an unsigned type, avoiding undefined behavior.
Signed-off-by: Yu-Chun Lin eleanor15x@gmail.com Link: https://patch.msgid.link/20250218081217.3468369-1-eleanor15x@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/sctp/stream.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/sctp/stream.c b/net/sctp/stream.c index ca8fdc9abca5f..08cd06078fab1 100644 --- a/net/sctp/stream.c +++ b/net/sctp/stream.c @@ -736,7 +736,7 @@ struct sctp_chunk *sctp_process_strreset_tsnreq( * value SHOULD be the smallest TSN not acknowledged by the * receiver of the request plus 2^31. */ - init_tsn = sctp_tsnmap_get_ctsn(&asoc->peer.tsn_map) + (1 << 31); + init_tsn = sctp_tsnmap_get_ctsn(&asoc->peer.tsn_map) + (1U << 31); sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL, init_tsn, GFP_ATOMIC);