On 30.01.2024 19:37, Andrew Cooper wrote: > Tamas reported this UBSAN failure from fuzzing: > > (XEN) > ================================================================================ > (XEN) UBSAN: Undefined behaviour in common/vsprintf.c:64:19 > (XEN) negation of -9223372036854775808 cannot be represented in type 'long > long int': > (XEN) ----[ Xen-4.19-unstable x86_64 debug=y ubsan=y Not tainted ]---- > ... > (XEN) Xen call trace: > (XEN) [<ffff82d040307c1c>] R ubsan.c#ubsan_epilogue+0xa/0xd9 > (XEN) [<ffff82d04030805d>] F __ubsan_handle_negate_overflow+0x99/0xce > (XEN) [<ffff82d04028868f>] F vsprintf.c#number+0x10a/0x93e > (XEN) [<ffff82d04028ac74>] F vsnprintf+0x19e2/0x1c56 > (XEN) [<ffff82d04030a47a>] F console.c#vprintk_common+0x76/0x34d > (XEN) [<ffff82d04030a79e>] F printk+0x4d/0x4f > (XEN) [<ffff82d04040c42b>] F do_hvm_op+0x288e/0x28f5 > (XEN) [<ffff82d04040d385>] F hvm_hypercall+0xad2/0x149a > (XEN) [<ffff82d0403cd072>] F vmx_vmexit_handler+0x1596/0x279c > (XEN) [<ffff82d0403d909b>] F vmx_asm_vmexit_handler+0xdb/0x200 > > The problem is an unsigned -> signed converstion because of a bad > formatter (%ld trying to format an unsigned long). > > We could fix it by swapping to %lu, but this is a useless printk() even in > debug builds, so just drop it completely. > > Reported-by: Tamas K Lengyel <[email protected]> > Signed-off-by: Andrew Cooper <[email protected]>
Acked-by: Jan Beulich <[email protected]>
