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sunrpc: Suppress GCC -Os warning on user2netname

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GCC with -Os warns that sprint might overflow:

  netname.c: In function ‘user2netname’:
  netname.c:51:28: error: ‘%s’ directive writing up to 255 bytes into a
  region of size between 239 and 249 [-Werror=format-overflow=]
     51 |   sprintf (netname, "%s.%d@%s", OPSYS, uid, dfltdom);
        |                            ^~               ~~~~~~~
  netname.c:51:3: note: ‘sprintf’ output between 8 and 273 bytes into a
  destination of size 256
     51 |   sprintf (netname, "%s.%d@%s", OPSYS, uid, dfltdom);
        |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  cc1: all warnings being treated as errors

However the code does test prior the sprintf call that dfltdom plus
the required extra space for OPSYS, uid, and extra character will not
overflow and return 0 instead.

Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Adhemerval Zanella Netto 2022-09-21 10:51:07 -03:00 committed by Adhemerval Zanella
parent cbf24edbb3
commit 6128e82ebe
1 changed files with 6 additions and 0 deletions
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6
sunrpc/netname.c
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@ -20,6 +20,7 @@
#include <string.h>
#include <rpc/rpc.h>
#include <shlib-compat.h>
#include <libc-diag.h>
#include "nsswitch.h"
@ -48,7 +49,12 @@ user2netname (char netname[MAXNETNAMELEN + 1], const uid_t uid,
if ((strlen (dfltdom) + OPSYS_LEN + 3 + MAXIPRINT) > (size_t) MAXNETNAMELEN)
return 0;
/* GCC with -Os warns that sprint might overflow while handling dfltdom,
however the above test does check if an overflow would happen. */
DIAG_PUSH_NEEDS_COMMENT;
DIAG_IGNORE_Os_NEEDS_COMMENT (8, "-Wformat-overflow");
sprintf (netname, "%s.%d@%s", OPSYS, uid, dfltdom);
DIAG_POP_NEEDS_COMMENT;
i = strlen (netname);
if (netname[i - 1] == '.')
netname[i - 1] = '\0';