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From: "andrea.righi at canonical dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/96367] New: bogus format truncation error on armhf when
 building perf with gcc 10
Date: Wed, 29 Jul 2020 12:43:00 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D96367

            Bug ID: 96367
           Summary: bogus format truncation error on armhf when building
                    perf with gcc 10
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: andrea.righi at canonical dot com
  Target Milestone: ---

After moving to gcc-10 (in Ubuntu Groovy) we're getting an error during the
perf build (only on the armhf architecture) when compiling the Linux kernel:

      util/map.c:124:5: error: =E2=80=98%s=E2=80=99 directive output may be=
 truncated writing
between 1 and 2147483645 bytes into a region of size 4096
[-Werror=3Dformat-truncation=3D]

Source code:

https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/groovy/t=
ree/tools/perf/util/map.c?h=3Dmaster-next#n117

Looking at the source code it seems to be a false positive: the snprintf()
should never exceed the size of 4096 as reported by the error (the new leng=
th
is checked immediately before calling snprintf).

Moreover, it is quite strange that we are getting this error only on armhf.=
 At
least I'm expecting to get this error across all architectures and not just
armhf.

Do you think it's a bug or am I missing something obvious? Thanks!=