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exec: Check for a pending fatal signal instead of core_state 

Prevent exec continuing when a fatal signal is pending by replacing
mmap_read_lock with mmap_read_lock_killable.  This is always the right
thing to do as userspace will never observe an exec complete when
there is a fatal signal pending.

With that change it becomes unnecessary to explicitly test for a core
dump in progress.  In coredump_wait zap_threads arranges under
mmap_write_lock for all tasks that use a mm to also have SIGKILL
pending, which means mmap_read_lock_killable will always return -EINTR
when old_mm->core_state is present.

Link: https://lkml.kernel.org/r/87fstux27w.fsf@disp2133
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2021-09-03 10:26:05 -05:00
parent 4f627af8e6
commit 7e3c4fb7fc
1 changed files with 6 additions and 8 deletions
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14
fs/exec.c
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@ -987,16 +987,14 @@ static int exec_mmap(struct mm_struct *mm)
if (old_mm) {
/*
* Make sure that if there is a core dump in progress
* for the old mm, we get out and die instead of going
* through with the exec. We must hold mmap_lock around
* checking core_state and changing tsk->mm.
* If there is a pending fatal signal perhaps a signal
* whose default action is to create a coredump get
* out and die instead of going through with the exec.
*/
mmap_read_lock(old_mm);
if (unlikely(old_mm->core_state)) {
mmap_read_unlock(old_mm);
ret = mmap_read_lock_killable(old_mm);
if (ret) {
up_write(&tsk->signal->exec_update_lock);
return -EINTR;
return ret;
}
}