Interesting; the crash is inside the amdgpu video driver. A similar crash log can be found at Bug #1981943 “kernel null pointer dereference on resume w/ amdgp...” : Bugs : linux package : Ubuntu (that machine apparently had Radeon RX 6700/6700 XT/6800M), but there is no solution there.
I also have AMD Radeon RX 5700 XT, but a different display (a single Iiyama XUB2792UHSU 27" 3840x2160), and did not notice any problems like that (but of course I did not actually test the install image for a long time; the installed system, however, uses the same 5.15.106 kernel at the moment).
The crashing function is apparently update_config() in amdgpu_dm_hdcp.c « amdgpu_dm « display « amd « drm « gpu « drivers - kernel/git/stable/linux.git - Linux kernel stable tree.
Now, because I have the exact same kernel module here, I can find where the update_config+0x103 address points to:
209d13: 49 8b 84 24 d0 04 00 mov 0x4d0(%r12),%rax
209d1a: 00
209d1b: 49 8b bc 24 d8 04 00 mov 0x4d8(%r12),%rdi
209d22: 00
>>209d23: 8b 30 mov (%rax),%esi
209d25: e8 00 00 00 00 callq 209d2a <update_config+0x10a>
209d26: R_X86_64_PLT32 dc_link_is_hdcp14-0x4
209d2a: 88 83 20 0f 00 00 mov %al,0xf20(%rbx)
209d30: 49 8b 84 24 d8 04 00 mov 0x4d8(%r12),%rax
209d37: 00
209d38: 0f b6 80 68 01 00 00 movzbl 0x168(%rax),%eax
The crashing instruction loads the second argument for dc_link_is_hdcp14() into %esi, which corresponds to this piece of C code:
link->hdcp_supported_informational = dc_link_is_hdcp14(aconnector->dc_link,
aconnector->dc_sink->sink_signal) ? 1 : 0;
And apparently aconnector->dc_sink is NULL here.
Note also that there is a NULL check above that code:
if (aconnector->dc_sink != NULL)
link->mode = mod_hdcp_signal_type_to_operation_mode(aconnector->dc_sink->sink_signal);
So apparently the case when aconnector->dc_sink is NULL was expected, but the check was not added in all places where it is actually required.
Apparently in Linux 6.0-rc1 the update_config() function was changed, and the code now has the NULL check there (and some other problem with “emulated dc_sink” (whatever it is) was fixed): drm/amd/display: Take emulated dc_sink into account for HDCP · gregkh/linux@4d31819 · GitHub. However, that commit was not backported to the 5.15.y stable series (checked 5.15.107 and it’s not there too).
As a temporary workaround, you may try disconnecting all monitors except one; if this would allow the installer to start properly, you could then add something like
boot.kernelPackages = pkgs.linuxPackages_6_1;
to your system configuration, so that the installed system would use a newer kernel without this bug. Alternatively, you may try grabbing a nixos-unstable ISO image from https://channels.nixos.org/nixos-unstable (these images should use a 6.1.y kernel too, so you may be able to use them without messing with your monitors).
