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stdio: fix vfscanf with matches longer than INT_MAX (bug 27650)

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Patterns like %*[ can safely be used to match a great many characters,
and it's quite realisitic to use them for more than INT_MAX characters
from an IO stream.

With the previous approach, after INT_MAX characters (v)fscanf would
return successfully, indicating an end to the match, even though there
wasn't one.
This commit is contained in:
Alyssa Ross 2021-05-03 10:34:11 +02:00 committed by Florian Weimer
parent c2fd60a586
commit b03e4d7bd2
1 changed files with 4 additions and 9 deletions
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13
stdio-common/vfscanf-internal.c
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@ -2479,11 +2479,6 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
else
not_in = 0;
if (width < 0)
/* There is no width given so there is also no limit on the
number of characters we read. Therefore we set width to
a very high value to make the algorithm easier. */
width = INT_MAX;
#ifdef COMPILE_WSCANF
/* Find the beginning and the end of the scanlist. We are not
@ -2647,7 +2642,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
}
}
}
while (--width > 0 && inchar () != WEOF);
while ((width < 0 || --width > 0) && inchar () != WEOF);
out:
#else
char buf[MB_LEN_MAX];
@ -2732,7 +2727,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
}
}
if (--width <= 0)
if (width >= 0 && --width <= 0)
break;
}
while (inchar () != EOF);
@ -2884,7 +2879,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
assert (n <= MB_LEN_MAX);
str += n;
}
while (--width > 0 && inchar () != WEOF);
while ((width < 0 || --width > 0) && inchar () != WEOF);
out2:
#else
do
@ -2938,7 +2933,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
}
}
}
while (--width > 0 && inchar () != EOF);
while ((width < 0 || --width > 0) && inchar () != EOF);
#endif
if (__glibc_unlikely (now == read_in))