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Joseph Myers 1dbe841a67 Remove most vfprintf width/precision-dependent allocations (bug 14231, bug 26211).
The vfprintf implementation (used for all printf-family functions)
contains complicated logic to allocate internal buffers of a size
depending on the width and precision used for a format, using either
malloc or alloca depending on that size, and with consequent checks
for size overflow and allocation failure.

As noted in bug 26211, the version of that logic used when '$' plus
argument number formats are in use is missing the overflow checks,
which can result in segfaults (quite possibly exploitable, I didn't
try to work that out) when the width or precision is in the range
0x7fffffe0 through 0x7fffffff (maybe smaller values as well in the
wprintf case on 32-bit systems, when the multiplication by sizeof
(CHAR_T) can overflow).

All that complicated logic in fact appears to be useless.  As far as I
can tell, there has been no need (outside the floating-point printf
code, which does its own allocations) for allocations depending on
width or precision since commit
3e95f6602b ("Remove limitation on size
of precision for integers", Sun Sep 12 21:23:32 1999 +0000).  Thus,
this patch removes that logic completely, thereby fixing both problems
with excessive allocations for large width and precision for
non-floating-point formats, and the problem with missing overflow
checks with such allocations.  Note that this does have the
consequence that width and precision up to INT_MAX are now allowed
where previously INT_MAX / sizeof (CHAR_T) - EXTSIZ or more would have
been rejected, so could potentially expose any other overflows where
the value would previously have been rejected by those removed checks.

I believe this completely fixes bugs 14231 and 26211.

Excessive allocations are still possible in the floating-point case
(bug 21127), as are other integer or buffer overflows (see bug 26201).
This does not address the cases where a precision larger than INT_MAX
(embedded in the format string) would be meaningful without printf's
return value overflowing (when it's used with a string format, or %g
without the '#' flag, so the actual output will be much smaller), as
mentioned in bug 17829 comment 8; using size_t internally for
precision to handle that case would be complicated by struct
printf_info being a public ABI.  Nor does it address the matter of an
INT_MIN width being negated (bug 17829 comment 7; the same logic
appears a second time in the file as well, in the form of multiplying
by -1).  There may be other sources of memory allocations with malloc
in printf functions as well (bug 24988, bug 16060).  From inspection,
I think there are also integer overflows in two copies of "if ((width
-= len) < 0)" logic (where width is int, len is size_t and a very long
string could result in spurious padding being output on a 32-bit
system before printf overflows the count of output characters).

Tested for x86-64 and x86.

(cherry picked from commit 6caddd34bd)
2022-08-30 10:09:13 +02:00
argp Update copyright dates with scripts/update-copyrights. 2020-01-01 00:14:33 +00:00
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elf Fix SXID_ERASE behavior in setuid programs (BZ #27471) 2021-04-14 10:50:14 +05:30
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htl htl: Add internal version of __pthread_mutex_timedlock 2020-01-13 20:41:07 +01:00
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iconv iconv: Fix incorrect UCS4 inner loop bounds (BZ#26923) 2021-01-03 13:20:30 +01:00
iconvdata gconv: Do not emit spurious NUL character in ISO-2022-JP-3 (bug 28524) 2021-12-05 12:04:05 +01:00
include <shlib-compat.h>: Support compat_symbol_reference for _ISOMAC 2022-01-18 11:16:50 +01:00
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intl intl: Handle translation output codesets with suffixes [BZ #26383] 2020-10-10 14:51:27 +02:00
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locale Fix locale/tst-locale-locpath cross-testing when sshd sets LANG. 2020-01-24 17:23:07 +00:00
localedata oc_FR locale: Fix spelling of April (bug 25639) 2020-05-09 17:07:24 +02:00
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malloc tests-mcheck: New variable to run tests with MALLOC_CHECK_=3 2020-12-24 11:20:34 +05:30
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misc Revert "Fix __minimal_malloc segfaults in __mmap due to stack-protector" 2021-12-16 15:18:31 +01:00
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nptl nptl: Zero-extend arguments to SETXID syscalls [BZ #26248] 2020-07-29 23:18:33 +02:00
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nscd nscd: Fix double free in netgroupcache [BZ #27462] 2021-03-08 15:41:29 +05:30
nss Disable warnings due to deprecated libselinux symbols used by nss and nscd 2020-07-29 20:33:35 +02:00
po Add Portuguese (Portugal) translation 2020-02-01 17:16:54 +05:30
posix wordexp: handle overflow in positional parameter number (bug 28011) 2021-07-06 21:04:26 +02:00
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stdio-common Remove most vfprintf width/precision-dependent allocations (bug 14231, bug 26211). 2022-08-30 10:09:13 +02:00
stdlib support: Add capability to fork an sgid child 2021-04-14 10:48:13 +05:30
string string: Add a testcase for wcsncmp with SIZE_MAX [BZ #28755] 2022-02-17 11:33:07 -08:00
sunrpc CVE-2022-23218: Buffer overflow in sunrpc svcunix_create (bug 28768) 2022-01-18 11:17:44 +01:00
support support: Add helpers to create paths longer than PATH_MAX 2022-08-18 00:14:28 +02:00
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abi-tags Remove the bulk of the NaCl port. 2017-05-20 08:09:10 -04:00
aclocal.m4 LIBC_SLIBDIR_RTLDDIR: substitute arguments in single quotes 2018-01-25 17:20:28 +01:00
config.h.in sparc: Assume GOTDATA support in the toolchain 2019-10-09 19:15:33 +02:00
config.make.in Make --bindir effective 2019-05-14 11:04:33 -03:00
configure Improve IFUNC check [BZ #25506] 2020-03-08 13:44:12 +01:00
configure.ac Improve IFUNC check [BZ #25506] 2020-03-08 13:44:12 +01:00
COPYING
COPYING.LIB
extra-lib.mk Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
gen-locales.mk Improve gen-locales.mk and gen-locale.sh to make test files with @ options work 2018-02-27 17:01:57 +01:00
INSTALL Linux: Require properly configured /dev/pts for PTYs 2022-08-18 12:28:36 +02:00
libc-abis libc-abis: Define ABSOLUTE ABI [BZ #19818][BZ #23307] 2018-07-05 18:06:43 +01:00
libof-iterator.mk Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
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Rules tests-mcheck: New variable to run tests with MALLOC_CHECK_=3 2020-12-24 11:20:34 +05:30
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version.h Update version numbers for 2.31 release 2020-02-01 17:16:54 +05:30

This directory contains the sources of the GNU C Library.
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