CVE-2026-90386

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

State: Published
Severity: Not scored
Published: Sep 17, 2026
Updated: Oct 19, 2026
Reserved: Sep 11, 2026

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.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 5650b013e6bfc14c8b30be727f4a715b01860a08Affected 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 63110ccc434e10d9e9d2c7d82ebfa8a6f9cedd94Affected 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 3a1c35739efb69e8ec2a868113a0471a01bb8f29Affected 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 111f559e5b6461f5f6977275716e6c5d1eb7ea27Affected 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 754533e6169d1f10bdef7a6ba9bd7740b524e1d4Affected 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 9eaac0cb4ca94e2e32c53c156ae5b813ba7ef90cAffected 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 618dd640ded6b94bbdb79c798a901ec564797033Affected 1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 038cf48b3170af26a70bf2dee4f8c3ac910f5176Affected
LinuxLinux	5.0Affected before 5.0Not affected 5.10.270 through 5.10.Not affected 5.15.221 through 5.15.Not affected 6.1.188 through 6.1.Not affected 6.6.157 through 6.6.Not affected 6.12.110 through 6.12.Not affected 6.18.52 through 6.18.Not affected 7.2.6 through 7.2.*Not affected 7.3 and laterNot affected

Product

Versions

LinuxLinux

1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 5650b013e6bfc14c8b30be727f4a715b01860a08Affected
1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 63110ccc434e10d9e9d2c7d82ebfa8a6f9cedd94Affected
1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 3a1c35739efb69e8ec2a868113a0471a01bb8f29Affected
1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 111f559e5b6461f5f6977275716e6c5d1eb7ea27Affected
1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 754533e6169d1f10bdef7a6ba9bd7740b524e1d4Affected
1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 9eaac0cb4ca94e2e32c53c156ae5b813ba7ef90cAffected
1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 618dd640ded6b94bbdb79c798a901ec564797033Affected
1dd728f5d4d4b8b53196c1e0fcf86bbaaee39cef to before 038cf48b3170af26a70bf2dee4f8c3ac910f5176Affected

LinuxLinux

5.0Affected
before 5.0Not affected
5.10.270 through 5.10.*Not affected
5.15.221 through 5.15.*Not affected
6.1.188 through 6.1.*Not affected
6.6.157 through 6.6.*Not affected
6.12.110 through 6.12.*Not affected
6.18.52 through 6.18.*Not affected
7.2.6 through 7.2.*Not affected
7.3 and laterNot affected

References

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