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posix: Fix posix_spawnp to not execute invalid binaries in non compat mode (BZ#23264)

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Current posix_spawnp implementation wrongly tries to execute invalid
binaries (for instance script without shebang) as a shell script in
non compat mode.  It was a regression introduced by
9ff72da471 when __spawni started to use
__execvpe instead of __execve (glibc __execvpe try to execute ENOEXEC
as shell script regardless).

This patch fixes it by using an internal symbol (__execvpex) with the
faulty semantic (since compat mode is handled by spawni.c itself).

It was reported by Daniel Drake on libc-help [1].

Checked on x86_64-linux-gnu and i686-linux-gnu.

	[BZ #23264]
	* include/unistd.h (__execvpex): New prototype.
	* posix/Makefile (tests): Add tst-spawn4.
	(tests-internal): Add tst-spawn4-compat.
	* posix/execvpe.c (__execvpe_common, __execvpex): New functions.
	* posix/tst-spawn4-compat.c: New file.
	* posix/tst-spawn4.c: Likewise.
	* sysdeps/unix/sysv/linux/spawni.c (__spawni): Do not interpret invalid
	binaries as shell scripts.
	* sysdeps/posix/spawni.c (__spawni): Likewise.

[1] https://sourceware.org/ml/libc-help/2018-06/msg00012.html
This commit is contained in:
Adhemerval Zanella
2018-06-06 14:07:34 -03:00
parent 67c0579669
commit 283d985122
8 changed files with 175 additions and 11 deletions
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26
posix/execvpe.c
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@ -67,11 +67,9 @@ maybe_script_execute (const char *file, char *const argv[], char *const envp[])
__execve (new_argv[0], new_argv, envp);
}
/* Execute FILE, searching in the `PATH' environment variable if it contains
no slashes, with arguments ARGV and environment from ENVP. */
int
__execvpe (const char *file, char *const argv[], char *const envp[])
static int
__execvpe_common (const char *file, char *const argv[], char *const envp[],
bool exec_script)
{
/* We check the simple case first. */
if (*file == '\0')
@ -85,7 +83,7 @@ __execvpe (const char *file, char *const argv[], char *const envp[])
{
__execve (file, argv, envp);
if (errno == ENOEXEC)
if (errno == ENOEXEC && exec_script)
maybe_script_execute (file, argv, envp);
return -1;
@ -137,7 +135,7 @@ __execvpe (const char *file, char *const argv[], char *const envp[])
__execve (buffer, argv, envp);
if (errno == ENOEXEC)
if (errno == ENOEXEC && exec_script)
/* This has O(P*C) behavior, where P is the length of the path and C
is the argument count. A better strategy would be allocate the
substitute argv and reuse it each time through the loop (so it
@ -184,4 +182,18 @@ __execvpe (const char *file, char *const argv[], char *const envp[])
return -1;
}
/* Execute FILE, searching in the `PATH' environment variable if it contains
no slashes, with arguments ARGV and environment from ENVP. */
int
__execvpe (const char *file, char *const argv[], char *const envp[])
{
return __execvpe_common (file, argv, envp, true);
}
weak_alias (__execvpe, execvpe)
/* Same as __EXECVPE, but does not try to execute NOEXEC files. */
int
__execvpex (const char *file, char *const argv[], char *const envp[])
{
return __execvpe_common (file, argv, envp, false);
}