[Bug 1844817] Re: trace: dynamic width format syntax not validated

[Philippe Mathieu-Daudé]

** Changed in: qemu
       Status: New => Fix Committed

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Title:
  trace: dynamic width format syntax not validated

Status in QEMU:
  Fix Committed

Bug description:
  The dtrace via stap backend cannot support the dynamic '*' width
  format.

  Eric noted in https://lists.gnu.org/archive/html/qemu-
  devel/2019-09/msg04720.html:

    https://sourceware.org/systemtap/langref.pdf

    section 9.2 printf, states:

    "The printf formatting directives are similar to those of C, except that
    they are fully checked for type by the translator."

    and does NOT list handling for '*' under precision or width.

  Some trace events have been merged without checking this:

  $ git ls-files|fgrep trace-event|xargs git grep '*\("\|x\)'
  hw/block/trace-events:11:pflash_io_read(uint64_t offset, int width, int 
fmt_width, uint32_t value, uint8_t cmd, uint8_t wcycle) "offset:0x%04"PRIx64" 
width:%d value:0x%0*x cmd:0x%02x wcycle:%u"
  hw/block/trace-events:12:pflash_io_write(uint64_t offset, int width, int 
fmt_width, uint32_t value, uint8_t wcycle) "offset:0x%04"PRIx64" width:%d 
value:0x%0*x wcycle:%u"
  hw/block/trace-events:13:pflash_data_read(uint64_t offset, int width, 
uint32_t value) "data offset:0x%04"PRIx64" value:0x%0*x"
  hw/block/trace-events:14:pflash_data_write(uint64_t offset, int width, 
uint32_t value, uint64_t counter) "data offset:0x%04"PRIx64" value:0x%0*x 
counter:0x%016"PRIx64
  hw/mips/trace-events:2:gt64120_read(const char *regname, int width, uint64_t 
value) "gt64120 read %s value:0x%0*" PRIx64
  hw/mips/trace-events:3:gt64120_write(const char *regname, int width, uint64_t 
value) "gt64120 write %s value:0x%0*" PRIx64

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