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hush: fix G.argv0_for_re_execing to avoid endless loop

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When the busybox is used as /sbin/init and the inittab file contains
below:

::respawn:-/bin/sh

/sbin/init spawns hush for the first time with the argv[0] contains '-',
and hush treats it as login shell.  Then it reads /etc/profile and if
the file contains the command execution like below, it invokes hush as
login shell because the argv[0] argument is still '-/bin/sh' and reads
/etc/profile again.  This will last until some failure (e.g., memory
failure) happens.

  [ "$(id -u)" -eq 0 ] && PS1="${PS1}# " || PS1="${PS1}\$ "

This commit fixes this issues by adding an offset (+1) to the
G.argv0_for_re_execing variable.

This issue happens on our out-of-tree UML (use mode linux) with nommu
configuration.

Link: https://lore.kernel.org/all/cover.1731290567.git.thehajime@gmail.com/
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Hajime Tazaki 2024-11-25 14:08:36 +09:00 • committed by Denys Vlasenko
parent 75ca8d074b
commit 23db689683
1 changed files with 3 additions and 0 deletions
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3
shell/hush.c
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@ -10361,6 +10361,9 @@ int hush_main(int argc, char **argv)
_exit(0);
}
G.argv0_for_re_execing = argv[0];
if (G.argv0_for_re_execing[0] == '-')
/* reexeced hush should never be a login shell */
G.argv0_for_re_execing++;
#endif
#if ENABLE_HUSH_TRAP
# if ENABLE_HUSH_FUNCTIONS