This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH] Fix segfault in maybe_script_execute.
On Sep 06 2018, Stefan Liebler <stli@linux.ibm.com> wrote:
> commit 6359e1c59f856a1115fdbcfa233052ac62e32c83
> Author: Stefan Liebler <stli@linux.ibm.com>
> Date: Thu Sep 6 11:03:38 2018 +0200
>
> Fix segfault in maybe_script_execute.
>
> If glibc is built with gcc 8 and -march=z900,
> the testcase posix/tst-spawn4-compat crashes with a segfault.
>
> In function maybe_script_execute, the new_argv array is dynamically
> initialized on stack with (argc + 1) elements.
> The function wants to add _PATH_BSHELL as the first argument
> and writes out of bounds of new_argv.
>
> In case of argc == 1, it writes three instead of two elements:
> new_argv[0] = (char *) _PATH_BSHELL;
> new_argv[1] = (char *) args->file;
> new_argv[2] = NULL;
>
> The latter write access writes to the same location where the
> pointer args is stored on stack. Then it segfaults while accessing args:
> args->exec (new_argv[0], new_argv, args->envp);
>
> In case of argc > 1, new_argv[0] and new_argv[1] are set in the same
This still make a difference between argc == 1 and argc > 1. Just say
that there is an off-by-one because maybe_script_execute fails to count
the terminating NULL when sizing new_argv.
Andreas.
--
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."