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Re: [PATCH] Fix segfault in maybe_script_execute.

On Sep 06 2018, Stefan Liebler <> wrote:

> commit 6359e1c59f856a1115fdbcfa233052ac62e32c83
> Author: Stefan Liebler <>
> 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 Schwab, SUSE Labs,
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