CVE-2026-90386i3c: dw: avoid shift-out-of-bounds when DAA assigns no devices

Official description

In the Linux kernel, the following vulnerability has been resolved: i3c: dw: avoid shift-out-of-bounds when DAA assigns no devices 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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/5650b013e6bfc14c8b30be727f4a715b01860a08
• https://git.kernel.org/stable/c/63110ccc434e10d9e9d2c7d82ebfa8a6f9cedd94
• https://git.kernel.org/stable/c/3a1c35739efb69e8ec2a868113a0471a01bb8f29
• https://git.kernel.org/stable/c/111f559e5b6461f5f6977275716e6c5d1eb7ea27
• https://git.kernel.org/stable/c/754533e6169d1f10bdef7a6ba9bd7740b524e1d4
• https://git.kernel.org/stable/c/9eaac0cb4ca94e2e32c53c156ae5b813ba7ef90c
• https://git.kernel.org/stable/c/618dd640ded6b94bbdb79c798a901ec564797033
• https://git.kernel.org/stable/c/038cf48b3170af26a70bf2dee4f8c3ac910f5176