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If you still think this bug report here is valid, then please switch the state back to "New" within the next 60 days, otherwise this report will be marked as "Expired". Or please mark it as "Fix Released" if the problem has been solved with a newer version of QEMU already. Thank you and sorry for the inconvenience. ** Changed in: qemu Status: New => Incomplete -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1849894 Title: hw/scsi/scsi-disk.c line 2554 allocation overflow Status in QEMU: Incomplete Bug description: When compiling qemu from git master (at commit 03bf012e523ecdf047ac56b2057950247256064d ) on Linux amd64, with gcc-9 9.2.1 , and using `-march=native -flto`, during linking of most target binaries, compiler does detect an issue with allocation in scsi_disk_new_request_dump and aborts compilation. make[1]: Entering directory '/home/user/qemu/slirp' make[1]: Nothing to be done for 'all'. make[1]: Leaving directory '/home/user/qemu/slirp' nm: stats64.o: no symbols LINK aarch64-softmmu/qemu-system-aarch64 In function ‘scsi_disk_new_request_dump’, inlined from ‘scsi_new_request’ at hw/scsi/scsi-disk.c:2580:9, inlined from ‘scsi_new_request’ at hw/scsi/scsi-disk.c:2564:21: hw/scsi/scsi-disk.c:2554:19: error: argument 1 value ‘18446744073709551612’ exceeds maximum object size 9223372036854775807 [-Werror=alloc-size-larger-than=] hw/scsi/scsi-disk.c: In function ‘scsi_new_request’: /usr/include/glib-2.0/glib/gmem.h:78:10: note: in a call to allocation function ‘g_malloc’ declared here 78 | gpointer g_malloc (gsize n_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE(1); | ^ lto1: all warnings being treated as errors lto-wrapper: fatal error: c++ returned 1 exit status compilation terminated. /usr/bin/ld: error: lto-wrapper failed collect2: error: ld returned 1 exit status same happens for most other targets: alpha-softmmu/qemu-system-alpha arm-softmmu/qemu-system-arm hppa-softmmu/qemu-system-hppa i386-softmmu /qemu-system-i386 lm32-softmmu/qemu-system-lm32 mips-softmmu/qemu- system-mips mips64-softmmu/qemu-system-mips64 mips64el-softmmu/qemu- system-mips64el mipsel-softmmu/qemu-system-mipsel ppc-softmmu/qemu- system-ppc ppc64-softmmu/qemu-system-ppc64 riscv32-softmmu/qemu- system-riscv32 riscv64-softmmu/qemu-system-riscv64 s390x-softmmu/qemu- system-s390x sh4-softmmu/qemu-system-sh4 sh4eb-softmmu/qemu-system- sh4eb sparc-softmmu/qemu-system-sparc sparc64-softmmu/qemu-system- sparc64 x86_64-softmmu/qemu-system-x86_64 xtensa-softmmu/qemu-system- xtensa xtensaeb-softmmu/qemu-system-xtensaeb Notice -softmmu being a common factor here. The size of the allocation for the temporary buffer for dumping using snprintf is determined based on the size of the buffer via call to scsi_cdb_length. I believe the heavy inlining and constant propagation makes scsi_cdb_length return -1, so len = -1. Then allocation size is 5*len + 1, or -4. Which overflows to 2^64 - 4 or so. The case of len==-1 from scsi_cdb_length happens if the (buf[0] >> 5) is not 0, 1, 2, 4 or 5. However, I can't find out how gcc figures out that buf[0] is not one of these variables. To me looking at this function, compiler should not know anything about buf[0]. I tried following the chain of calls back, including devirtualize alloc_req, and I found scsi_device_alloc_req calling these alloc_req callbacks, but it is itself called from scsi_req_new, which is called in get_scsi_requests , just after buf is filled from QEMUFile using qemu_get_buffer, which ultimately goes even further into read paths, which there might be many AFAIK. glib2 version 2.62.1-1 To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1849894/+subscriptions