Re: unrandomize issue with glibc 2.36.9000 and _FORTIFY_SOURCE

[Camm Maguire]

Greetings, and thanks as always for the heads up.

Do you have an estimate for when this libc and/or gcc-13 hits the fedora
release cycle?

Take care,

Jerry James <loganjerry@gmail.com> writes:

> A new snapshot of the upcoming glibc 2.37 (called 2.36.9000) has
> landed in Fedora, and now gcl 2.6.14 does this while running
> configure:
>
> checking for personality(ADDR_NO_RANDOMIZE) support... no
> checking that sbrk is (now) non-random... no
> Cannot build with randomized sbrk. Your options:
>  - upgrade to a kernel/libc that knows about personality(ADDR_NO_RANDOMIZE)
>  - recompile your kernel with CONFIG_COMPAT_BRK (if it has that option)
>  - run sysctl kernel.randomize_va_space=0 before using gcl
> configure: error: exiting
>
> And config.log is full of errors:
>
> configure:8097: checking for personality(ADDR_NO_RANDOMIZE) support
> configure:8117: gcc -o conftest -O2 -fexceptions -g
> -grecord-gcc-switches -pipe -Wall -Werror=format-security
> -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS
> -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic
> -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection
> -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -fsigned-char
> -pipe -fcommon -fno-builtin-malloc -fno-builtin-free -fno-PIE -fno-pie
> -fno-PIC -fno-pic -Wall -Wno-empty-body -Wno-unused-but-set-variable
> -I/usr/include/tirpc  -Wl,-z,relro -Wl,--as-needed
> -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1  -Wl,--build-id=sha1
> -no-pie conftest.c  >&5
> In file included from /usr/include/unistd.h:1214,
>                  from h/unrandomize.h:4,
>                  from conftest.c:64:
> /usr/include/bits/unistd.h: In function 'main':
> /usr/include/bits/unistd.h:36:1: error: nested function 'read' declared 
> 'extern'
>    36 | read (int __fd, void *__buf, size_t __nbytes)
>       | ^~~~
> /usr/include/bits/unistd.h:36:1: error: static declaration of 'read'
> follows non-static declaration
> /usr/include/unistd.h:371:16: note: previous declaration of 'read'
> with type 'ssize_t(int,  void *, size_t)' {aka 'long int(int,  void *,
> long unsigned int)'}
>   371 | extern ssize_t read (int __fd, void *__buf, size_t __nbytes) __wur
>       |                ^~~~
> /usr/include/bits/unistd.h:72:1: error: nested function 'pread'
> declared 'extern'
>    72 | pread (int __fd, void *__buf, size_t __nbytes, __off_t __offset)
>       | ^~~~~
> /usr/include/bits/unistd.h:72:1: error: static declaration of 'pread'
> follows non-static declaration
> /usr/include/unistd.h:389:16: note: previous declaration of 'pread'
> with type 'ssize_t(int,  void *, size_t,  __off_t)' {aka 'long
> int(int,  void *, long unsigned int,  long int)'}
>   389 | extern ssize_t pread (int __fd, void *__buf, size_t __nbytes,
>       |                ^~~~~
> /usr/include/bits/unistd.h:90:1: error: nested function 'pread64'
> declared 'extern'
>    90 | pread64 (int __fd, void *__buf, size_t __nbytes, __off64_t __offset)
>       | ^~~~~~~
> /usr/include/bits/unistd.h:90:1: error: static declaration of
> 'pread64' follows non-static declaration
> /usr/include/unistd.h:422:16: note: previous declaration of 'pread64'
> with type 'ssize_t(int,  void *, size_t,  __off64_t)' {aka 'long
> int(int,  void *, long unsigned int,  long int)'}
>   422 | extern ssize_t pread64 (int __fd, void *__buf, size_t __nbytes,
>       |                ^~~~~~~
> In file included from /usr/include/features.h:490,
>                  from /usr/include/bits/libc-header-start.h:33,
>                  from /usr/include/stdio.h:27,
>                  from conftest.c:61:
> /usr/include/bits/unistd.h:116:1: error: nested function 'readlink'
> declared 'extern'
>   116 | __NTH (readlink (const char *__restrict __path, char *__restrict 
> __buf,
>       | ^~~~~
> /usr/include/bits/unistd.h:116:1: error: static declaration of
> 'readlink' follows non-static declaration
> /usr/include/unistd.h:838:16: note: previous declaration of 'readlink'
> with type 'ssize_t(const char * restrict,  char * restrict,  size_t)'
> {aka 'long int(const char * restrict,  char * restrict,  long unsigned
> int)'}
>   838 | extern ssize_t readlink (const char *__restrict __path,
>
>
> and so on.  The problem is h/unrandomize.h, which starts with #include
> directives, then has code meant to be embedded in a function.
> Apparently the combination of that with -O2 and
> -Wp,-D_FORTIFY_SOURCE=3 (or 2) leads to the errors above.  Here is the
> definition of read from /usr/include/bits/unistd.h, for example:
>
> __fortify_function __wur ssize_t
> read (int __fd, void *__buf, size_t __nbytes)
> {
>   return __glibc_fortify (read, __nbytes, sizeof (char),
>               __glibc_objsize0 (__buf),
>               __fd, __buf, __nbytes);
> }
>
> I don't know offhand where or how __fortify_function or
> __glibc_fortify are defined, but note the "nested function" parts of
> the errors above.  That read() function is a full definition, so when
> it appears inside a function body, that makes it a nested function,
> which makes it fail to match the unfortified function declaration.
>
> The attached patch may not be optimal, but seems to solve this
> problem.  Then the GCC 13 prerelease version we are using seems to be
> causing another problem that I haven't had time to diagnose yet.  More
> on that later.

-- 
Camm Maguire                                        camm@maguirefamily.org
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