exec: move allow_write_access/fput to exec_binprm() (52f14282) · Commits · 戴 / test

When search_binary_handler() succeeds it does allow_write_access() and fput(), then it clears bprm->file to ensure the caller will not do the same. We can simply move this code to exec_binprm() which is called only once. In fact we could move this to free_bprm() and remove the same code in do_execve_common's error path. Signed-off-by:

Oleg Nesterov <oleg@redhat.com> Acked-by:

Kees Cook <keescook@chromium.org> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Evgeniy Polyakov <zbr@ioremap.net> Cc: Zach Levis <zml@linux.vnet.ibm.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/exec.c

+6 −4

Original line number	Original line	Diff line number	Diff line
	@@ -1400,10 +1400,6 @@ int search_binary_handler(struct linux_binprm *bprm)
	bprm->recursion_depth--;		bprm->recursion_depth--;
	if (retval >= 0) {		if (retval >= 0) {
	put_binfmt(fmt);		put_binfmt(fmt);
	allow_write_access(bprm->file);
	if (bprm->file)
	fput(bprm->file);
	bprm->file = NULL;
	return retval;		return retval;
	}		}
	read_lock(&binfmt_lock);		read_lock(&binfmt_lock);
	@@ -1455,6 +1451,12 @@ static int exec_binprm(struct linux_binprm *bprm)
	ptrace_event(PTRACE_EVENT_EXEC, old_vpid);		ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
	current->did_exec = 1;		current->did_exec = 1;
	proc_exec_connector(current);		proc_exec_connector(current);

			if (bprm->file) {
			allow_write_access(bprm->file);
			fput(bprm->file);
			bprm->file = NULL; /* to catch use-after-free */
			}
	}		}

	return ret;		return ret;

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