5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jakub Kicinski <kuba@kernel.org>
[ Upstream commit 038cf48b3170af26a70bf2dee4f8c3ac910f5176 ]
On an empty bus ENTDAA assigns nothing, so cmd->rx_len (the count
of addresses left unassigned) equals master->maxdevs.
The GENMASK() index master->maxdevs - cmd->rx_len - 1 then becomes -1,
which trips up UBSAN. This happens every time on boot on a Gigabyte/AMD
server:
UBSAN: shift-out-of-bounds in drivers/i3c/master/dw-i3c-master.c:905:12
shift exponent 64 is too large for 64-bit type 'long unsigned int'
CPU: 7 UID: 0 PID: 963 Comm: (udev-worker) Not tainted 7.0.11-200.fc44.x86_64 #1 PREEMPT(lazy)
Hardware name: Giga Computing E163-Z34-AAH1-000/MZ33-DC1-000, BIOS R32_F45 04/01/2026
Call Trace:
<TASK>
dump_stack_lvl+0x5d/0x80
ubsan_epilogue+0x5/0x2b
__ubsan_handle_shift_out_of_bounds.cold+0xd7/0x1ab
dw_i3c_master_daa.cold+0x1b/0x96 [dw_i3c_master]
i3c_master_do_daa_ext.part.0+0x3e/0xf0 [i3c]
Skip the mask when no new device was assigned.
Fixes: 1dd728f5d4d4 ("i3c: master: Add driver for Synopsys DesignWare IP")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260630172904.2662160-1-kuba@kernel.org (local)
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/i3c/master/dw-i3c-master.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
index 51a8608203de7..11b1cec6398f3 100644
--- a/drivers/i3c/master/dw-i3c-master.c
+++ b/drivers/i3c/master/dw-i3c-master.c
@@ -810,7 +810,15 @@ static int dw_i3c_master_daa(struct i3c_master_controller *m)
if (!wait_for_completion_timeout(&xfer->comp, XFER_TIMEOUT))
dw_i3c_master_dequeue_xfer(master, xfer);
- newdevs = GENMASK(master->maxdevs - cmd->rx_len - 1, 0);
+ /*
+ * cmd->rx_len holds the number of addresses ENTDAA left unassigned.
+ * On an empty bus rx_len == maxdevs, so avoid GENMASK(-1, 0).
+ */
+ if (cmd->rx_len >= master->maxdevs)
+ newdevs = 0;
+ else
+ newdevs = GENMASK(master->maxdevs - cmd->rx_len - 1, 0);
+
newdevs &= ~olddevs;
for (pos = 0; pos < master->maxdevs; pos++) {--
2.53.0