UBSAN: Undefined behaviour in ./arch/x86/include/asm/futex.h:53:13

[Toralf FÃrster]

Hello,

got this today at a stable Gentoo Linux with recent kernel :

Nov  1 05:29:46 mr-fox kernel: [231282.542520] ================================================================================
Nov  1 05:29:46 mr-fox kernel: [231282.542523] UBSAN: Undefined behaviour in ./arch/x86/include/asm/futex.h:53:13
Nov  1 05:29:46 mr-fox kernel: [231282.542525] shift exponent -849 is negative
Nov  1 05:29:46 mr-fox kernel: [231282.542527] CPU: 3 PID: 15032 Comm: futex Not tainted 4.13.10 #13
Nov  1 05:29:46 mr-fox kernel: [231282.542528] Hardware name:                  /DX79TO, BIOS SIX7910J.86A.0650.2014.0307.0138 03/07/2014
Nov  1 05:29:46 mr-fox kernel: [231282.542529] Call Trace:
Nov  1 05:29:46 mr-fox kernel: [231282.542535]  dump_stack+0x60/0x9a
Nov  1 05:29:46 mr-fox kernel: [231282.542539]  ? val_is_negative+0x2b/0x50
Nov  1 05:29:46 mr-fox kernel: [231282.542540]  ubsan_epilogue+0xd/0x40
Nov  1 05:29:46 mr-fox kernel: [231282.542542]  __ubsan_handle_shift_out_of_bounds+0x10d/0x170
Nov  1 05:29:46 mr-fox kernel: [231282.542545]  ? get_futex_key+0x38a/0x6e0
Nov  1 05:29:46 mr-fox kernel: [231282.542546]  do_futex+0xd72/0x1380
Nov  1 05:29:46 mr-fox kernel: [231282.542547]  ? do_futex+0xd72/0x1380
Nov  1 05:29:46 mr-fox kernel: [231282.542548]  SyS_futex+0x7a/0x180
Nov  1 05:29:46 mr-fox kernel: [231282.542551]  ? SyS_write+0x4f/0xc0
Nov  1 05:29:46 mr-fox kernel: [231282.542554]  entry_SYSCALL_64_fastpath+0x13/0x94
Nov  1 05:29:46 mr-fox kernel: [231282.542555] RIP: 0033:0x7fed8a79c829
Nov  1 05:29:46 mr-fox kernel: [231282.542556] RSP: 002b:00007fffadf04968 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
Nov  1 05:29:46 mr-fox kernel: [231282.542557] RAX: ffffffffffffffda RBX: 00007fed8aa55ae0 RCX: 00007fed8a79c829
Nov  1 05:29:46 mr-fox kernel: [231282.542558] RDX: badda7a0facefeed RSI: 0000000000000005 RDI: 00007fed8ae2bffc
Nov  1 05:29:46 mr-fox kernel: [231282.542559] RBP: 0000000000001011 R08: 00007fed8ae25ffc R09: 00000000a0caffee
Nov  1 05:29:46 mr-fox kernel: [231282.542560] R10: 000000000000000b R11: 0000000000000246 R12: 0000000000000000
Nov  1 05:29:46 mr-fox kernel: [231282.542560] R13: 00007fed8aa55b38 R14: 0000000000000000 R15: 0000000000001030
Nov  1 05:29:46 mr-fox kernel: [231282.542561] ================================================================================


-- 
Toralf
PGP C4EACDDE 0076E94E