public inbox for
 help / color / mirror / Atom feed
* Werror=format-security issue from gprofng/src/
@ 2022-06-07 14:49 Yichao Yu
       [not found] ` <>
  0 siblings, 1 reply; 3+ messages in thread
From: Yichao Yu @ 2022-06-07 14:49 UTC (permalink / raw)
  To: gdb

I got a format-security werror on gprofng/src/ when trying to
build the master version of gdb (the compiler flag is added by the
archlinuxcn build machine).

While I could disable the flag, I think there might be a real issue
looking at the code.

The line that causes the issue is,
which uses a "dynamic" format string without any argument. AFAICT, the
fmt3 is only ever initialized in
`er_print_experiment::overview_summary` and if I read it correctly,
it's initialized to a string with no actual formatting inputs other
than a `%%`. It is used, however, twice in
`er_print_experiment::overview_value`, one given two zeros as the
arguments and one given no arguments so it looks a bit suspicious.

The git log shows now history of this file so I'm not sure what's the
intention but my best guess is

1. the `fprintf (out_file, fmt3, 0., 0.);` was meant to be using
`fmt4`. (I assume this is to avoid nan from total_value = 0), or
2. since fmt3 is actually a string that's more or less "0.0 (0.0)"
with padding, the two `0.`s passed to fmt3 are probably bogus and it
should be the same as the `fprintf (out_file, fmt3);` below

if my understanding is correct, I think in either case one can simply
avoid using fmt3 with fprintf by just removing the extra % from it and
directly write it to the output instead. (i.e.
Did I miss anything?


^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2022-06-12 22:30 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-06-07 14:49 Werror=format-security issue from gprofng/src/ Yichao Yu
     [not found] ` <>
2022-06-10 17:20   ` Fwd: " Vladimir Mezentsev
2022-06-12 22:29     ` Yichao Yu

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).