unexpected errno: 95 with Linux kernel 6.12.9

[krichprollsch]

Upgrading to Linux kernel 6.12.9 generates an error(cli): Server listen error: error.Unexpected error.

$ zig build run                                                                                                 
unexpected errno: 95                                    
/usr/local/zig-0.13.0/lib/std/debug.zig:197:31: 0x1afab42 in dumpCurrentStackTrace (lightpanda)
        writeCurrentStackTrace(stderr, debug_info, io.tty.detectConfig(io.getStdErr()), start_addr) catch |err| {
                              ^                         
/usr/local/zig-0.13.0/lib/std/posix.zig:7320:40: 0x1aca138 in unexpectedErrno (lightpanda)                      
        std.debug.dumpCurrentStackTrace(null);                                                                  
                                       ^                                                                        
/usr/local/zig-0.13.0/lib/std/posix.zig:6715:49: 0x1ac5274 in setsockopt (lightpanda)
            else => |err| return unexpectedErrno(err),                                                          
                                                ^     
/home/pierre/wrk/browser/src/server.zig:493:29: 0x1ac5101 in setSockOpt (lightpanda)
    try std.posix.setsockopt(fd, level, option, &std.mem.toBytes(value));                               
                            ^                                                                                   
/home/pierre/wrk/browser/src/server.zig:510:23: 0x1ac54a8 in listen (lightpanda)
        try setSockOpt(sockfd, std.posix.SOL.SOCKET, std.posix.SO.REUSEPORT, 1);
                      ^                                                                                         
/home/pierre/wrk/browser/src/main.zig:261:41: 0x1aefb79 in main (lightpanda)
            const socket = server.listen(addr) catch |err| {                
                                        ^                                                                       
/usr/local/zig-0.13.0/lib/std/start.zig:524:37: 0x1af267e in main (lightpanda)                                  
            const result = root.main() catch |err| {                                                            
                                    ^                                                                           
../sysdeps/nptl/libc_start_call_main.h:58:16: 0x7fd1be5ccd67 in __libc_start_call_main (../sysdeps/x86/libc-start.c)
../csu/libc-start.c:360:3: 0x7fd1be5cce24 in __libc_start_main_impl (../sysdeps/x86/libc-start.c)               
???:?:?: 0x1ac3020 in ??? (???)
???:?:?: 0x0 in ??? (???)                                                                                       
error(cli): Server listen error: error.Unexpected

[joshbaptiste]

socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3
setsockopt(3, SOL_SOCKET, SO_REUSEPORT, [1], 4) = -1 EOPNOTSUPP (Operation not supported)
close(3)                          = 0
write(2, "error(cli): Server listen error:"..., 51) = 51

From strace output looks like kernel folks patched to not allow SO_REUSEPORT on Unix domain sockets anymore

[krichprollsch]

Oh good catch @joshbaptiste thanks!
I'm pushing a fix.

[TibixDev]

Just tried Lightpanda, I'm also getting this. I tried switching to LTS which is a much older version that's stable but it seems to not have helped.

❯ ./lightpanda-x86_64-linux --host 127.0.0.1 --port 9223
error(cli): Server listen error: error.Unexpected

usage: ./lightpanda-x86_64-linux [options] [URL]

  start Lightpanda browser

  * if an url is provided the browser will fetch the page and exit
  * otherwhise the browser starts a CDP server

  -h, --help      Print this help message and exit.
  --verbose       Display all logs. By default only info, warn and err levels are displayed.
  --host          Host of the CDP server (default "127.0.0.1")
  --port          Port of the CDP server (default "9222")
  --timeout       Timeout for incoming connections of the CDP server (in seconds, default "3")
  --dump          Dump document in stdout (fetch mode only)
error: Usage
❯ echo $?
1
❯ uname -a
Linux endeavour 6.6.70-1-lts #1 SMP PREEMPT_DYNAMIC Thu, 09 Jan 2025 13:22:24 +0000 x86_64 GNU/Linux

Maybe the patch was backported?

[krichprollsch]

@TibixDev thanks for your message.
The error is pretty generic, but it looks like it is the same.
I'm forcing a nightly build with the fix (https://github.com/lightpanda-io/browser/actions/runs/12911614829)
Could-you test once the CI is done please?

[joshbaptiste]

@TibixDev yea since it's considered a vulnerability, backported to LTS kernels including 6.6.70

[joshbaptiste]

josh@fedora ~ > sha1sum ./lightpanda-x86_64-linux.2 ; uname -a; ./lightpanda-x86_64-linux.2
0315fcbb44f49142f94bd5d07b7cc3fb57da3c0c  ./lightpanda-x86_64-linux.2
Linux fedora 6.12.9-200.fc41.x86_64 #1 SMP PREEMPT_DYNAMIC Thu Jan  9 16:05:40 UTC 2025 x86_64 GNU/Linux
info(websocket): starting blocking worker to listen on 127.0.0.1:9222
info(server): accepting new conn...

nightly works... thx @krichprollsch !