Lombard Report

Hello,

After updating a PowerBook Lombard (512 MiB, Xfce, wdm, sysvinit, 
yaboot), to the latest Debian SID and booting Debian's default 
initrd.img and kernel:

# uname -a
Linux lombard 6.16.5+deb14-powerpc #1 PREEMPT Debian 6.16.5-1 
(2025-09-05) ppc GNU/Linux

everything (including X11) works.

However, I do see the following warning message in the system log 
(dmesg), apparently from apparmor, which I normally disable but left 
running for this test. I'm not sure how to report or escalate the 
warning that triggered this "UBSAN" message, or whether it's even 
important or needs to be reported:

...
[  213.673323] UBSAN: shift-out-of-bounds in 
/build/reproducible-path/linux-6.16.5/arch/powerpc/net/bpf_jit_comp32.c:589:27
[  213.673364] shift exponent 32 is too large for 32-bit type 'int'
[  213.673404] CPU: 0 UID: 107 PID: 1886 Comm: sshd-auth Tainted: G 
   W           6.16.5+deb14-powerpc #1 PREEMPTLAZY  Debian 6.16.5-1
[  213.673451] Tainted: [W]=WARN
...

Booting back into a custom kernel and disabling apparmor, I see no 
warning messages. I'd be happy to do any testing on the Lombard if 
anyone has any ideas or interest in debugging the warning that triggered 
the UBSAN message.

Here's more of the relevant part of the dmesg output while apparmor was 
active:

# dmesg
...
[  213.673202] ------------[ cut here ]------------
[  213.673323] UBSAN: shift-out-of-bounds in 
/build/reproducible-path/linux-6.16.5/arch/powerpc/net/bpf_jit_comp32.c:589:27
[  213.673364] shift exponent 32 is too large for 32-bit type 'int'
[  213.673404] CPU: 0 UID: 107 PID: 1886 Comm: sshd-auth Tainted: G 
   W           6.16.5+deb14-powerpc #1 PREEMPTLAZY  Debian 6.16.5-1
[  213.673451] Tainted: [W]=WARN
[  213.673470] Hardware name: PowerBook1,1 740/750 0x88300 PowerMac
[  213.673496] Call Trace:
[  213.673515] [e30d59a0] [c0d93ea0] dump_stack_lvl+0x50/0x78 (unreliable)
[  213.673608] [e30d59c0] [c07efdb4] ubsan_epilogue+0x10/0x40
[  213.673682] [e30d59d0] [c07ef958] 
__ubsan_handle_shift_out_of_bounds+0x17c/0x238
[  213.673735] [e30d5a50] [c0075d84] bpf_jit_build_body+0x4d74/0x4fd4
[  213.673792] [e30d5b00] [c006fc58] bpf_int_jit_compile+0x35c/0x5b4
[  213.673839] [e30d5bb0] [c024ce50] bpf_prog_select_runtime+0x1e0/0x2c4
[  213.673913] [e30d5be0] [c0b1de68] bpf_prepare_filter+0x5f0/0x794
[  213.673974] [e30d5c30] [c0b1e1d0] bpf_prog_create_from_user+0xe8/0x158
[  213.674027] [e30d5c60] [c01bc718] do_seccomp+0x308/0xbb0
[  213.674080] [e30d5cb0] [c00aeb54] sys_prctl+0x51c/0xa64
[  213.674129] [e30d5d00] [c0015500] system_call_exception+0xa0/0x120
[  213.674191] [e30d5f30] [c00211ac] ret_from_syscall+0x0/0x2c
[  213.674245] ---- interrupt: c00 at 0xa74c3318
[  213.674294] NIP:  a74c3318 LR: 00543b40 CTR: 00000000
[  213.674321] REGS: e30d5f40 TRAP: 0c00   Tainted: G        W 
  (6.16.5+deb14-powerpc Debian 6.16.5-1)
[  213.674350] MSR:  0000d032 <EE,PR,ME,IR,DR,RI>  CR: 2800246c  XER: 
00000000
[  213.674449]
                GPR00: 000000ab afcea180 a7bfe9a0 00000016 00000002 
0063b468 afcea0c8 00000020
                GPR08: ffffffc0 000207d9 00008031 40146a9a 40146767 
0063f8d4 00000000 00000003
                GPR16: 006402b0 005e5a70 008e12c0 afcea20c 005e5ab4 
005d2388 00000000 00000000
                GPR24: 00640018 006402b8 005e1284 00640298 afcea224 
005db480 00645c60 005e7180
[  213.674806] NIP [a74c3318] 0xa74c3318
[  213.674835] LR [00543b40] 0x543b40
[  213.674862] ---- interrupt: c00
[  213.674884] ---[ end trace ]---