74 lines
2.6 KiB
Diff
74 lines
2.6 KiB
Diff
From e75cf4a58b5eaf482804e5e1b2cc7d4399df350e Mon Sep 17 00:00:00 2001
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From: Patrick Steinhardt <ps@pks.im>
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Date: Mon, 28 Aug 2017 20:57:19 +0200
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Subject: [PATCH 075/225] unix exec: avoid atexit handlers when child exits
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The `grub_util_exec_redirect_all` helper function can be used to
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spawn an executable and redirect its output to some files. After calling
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`fork()`, the parent will wait for the child to terminate with
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`waitpid()` while the child prepares its file descriptors, environment
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and finally calls `execvp()`. If something in the children's setup
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fails, it will stop by calling `exit(127)`.
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Calling `exit()` will cause any function registered via `atexit()` to be
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executed, which is usually the wrong thing to do in a child. And
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actually, one can easily observe faulty behaviour on musl-based systems
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without modprobe(8) installed: executing `grub-install --help` will call
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`grub_util_exec_redirect_all` with "modprobe", which obviously fails if
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modprobe(8) is not installed. Due to the child now exiting and invoking
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the `atexit()` handlers, it will clean up some data structures of the
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parent and cause it to be deadlocked in the `waitpid()` syscall.
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The issue can easily be fixed by calling `_exit(127)` instead, which is
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especially designed to be called when the atexit-handlers should not be
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executed.
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Signed-off-by: Patrick Steinhardt <ps@pks.im>
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---
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grub-core/osdep/unix/exec.c | 8 ++++----
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1 file changed, 4 insertions(+), 4 deletions(-)
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diff --git a/grub-core/osdep/unix/exec.c b/grub-core/osdep/unix/exec.c
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index 935ff120e..db3259f65 100644
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--- a/grub-core/osdep/unix/exec.c
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+++ b/grub-core/osdep/unix/exec.c
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@@ -99,7 +99,7 @@ grub_util_exec_redirect_all (const char *const *argv, const char *stdin_file,
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{
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fd = open (stdin_file, O_RDONLY);
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if (fd < 0)
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- exit (127);
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+ _exit (127);
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dup2 (fd, STDIN_FILENO);
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close (fd);
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}
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@@ -108,7 +108,7 @@ grub_util_exec_redirect_all (const char *const *argv, const char *stdin_file,
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{
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fd = open (stdout_file, O_WRONLY | O_CREAT, 0700);
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if (fd < 0)
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- exit (127);
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+ _exit (127);
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dup2 (fd, STDOUT_FILENO);
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close (fd);
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}
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@@ -117,7 +117,7 @@ grub_util_exec_redirect_all (const char *const *argv, const char *stdin_file,
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{
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fd = open (stderr_file, O_WRONLY | O_CREAT, 0700);
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if (fd < 0)
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- exit (127);
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+ _exit (127);
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dup2 (fd, STDERR_FILENO);
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close (fd);
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}
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@@ -126,7 +126,7 @@ grub_util_exec_redirect_all (const char *const *argv, const char *stdin_file,
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setenv ("LC_ALL", "C", 1);
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execvp ((char *) argv[0], (char **) argv);
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- exit (127);
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+ _exit (127);
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}
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waitpid (pid, &status, 0);
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if (!WIFEXITED (status))
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--
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2.14.3
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