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ed6a68bac7
The 7bb8045ec0 path made the '%n' fortify check ignore EMFILE errors
while trying to open /proc/self/maps, and this added a security
issue where EMFILE can be attacker-controlled thus making it
ineffective for some cases.
The EMFILE failure is reinstated but with a different error
message. Also, to improve the false positive of the hardening for
the cases where no new files can be opened, the
_dl_readonly_area now uses _dl_find_object to check if the
memory area is within a writable ELF segment. The procfs method is
still used as fallback.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Arjun Shankar <arjun@redhat.com>
57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
/* Testcase for BZ 30932.
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Copyright (C) 2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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static const char *str2 = "F";
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static char writeable_format[10] = "%s";
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static char relro_format[10] __attribute__ ((section (".data.rel.ro"))) =
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"%s%n%s%n";
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void
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init_writable (void)
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{
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strcpy (writeable_format + 2, "%n%s%n");
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}
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int
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sprintf_writable (int *n1, int *n2)
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{
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char buf[128];
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return sprintf (buf, writeable_format, str2, n1, str2, n2);
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}
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int
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sprintf_relro (int *n1, int *n2)
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{
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char buf[128];
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return sprintf (buf, relro_format, str2, n1, str2, n2);
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}
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int
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sprintf_writable_malloc (int *n1, int *n2)
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{
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char buf[128];
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char *buf2_malloc = strdup (writeable_format);
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if (buf2_malloc == NULL)
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abort ();
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return sprintf (buf, buf2_malloc, str2, n1, str2, n2);
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}
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