CVE-2026-90386

Summary

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 Software

VendorProductVersion RangeStatus
LinuxLinux1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef < 5650b013e6bfc14c8b30be727f4a715b01860a08affected
LinuxLinux1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef < 63110ccc434e10d9e9d2c7d82ebfa8a6f9cedd94affected
LinuxLinux1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef < 3a1c35739efb69e8ec2a868113a0471a01bb8f29affected
LinuxLinux1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef < 111f559e5b6461f5f6977275716e6c5d1eb7ea27affected
LinuxLinux1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef < 754533e6169d1f10bdef7a6ba9bd7740b524e1d4affected
LinuxLinux1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef < 9eaac0cb4ca94e2e32c53c156ae5b813ba7ef90caffected
LinuxLinux1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef < 618dd640ded6b94bbdb79c798a901ec564797033affected
LinuxLinux1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef < 038cf48b3170af26a70bf2dee4f8c3ac910f5176affected
LinuxLinux5.0affected
LinuxLinux0 < 5.0unaffected
LinuxLinux5.10.270 <= 5.10.*unaffected
LinuxLinux5.15.221 <= 5.15.*unaffected
LinuxLinux6.1.188 <= 6.1.*unaffected
LinuxLinux6.6.157 <= 6.6.*unaffected
LinuxLinux6.12.110 <= 6.12.*unaffected
LinuxLinux6.18.52 <= 6.18.*unaffected
LinuxLinux7.2.6 <= 7.2.*unaffected
LinuxLinux7.3-rc1 <= *unaffected

Weaknesses

References