vt: avoid a VLA in the unicode screen scroll function (d541ae4e) · Commits · 戴 / test

drivers/tty/vt/vt.c

+23 −13

Original line number	Diff line number	Diff line
		@@ -104,6 +104,7 @@
		#include <linux/kdb.h>
		#include <linux/ctype.h>
		#include <linux/bsearch.h>
		#include <linux/gcd.h>

		#define MAX_NR_CON_DRIVER 16

		@@ -434,20 +435,29 @@ static void vc_uniscr_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
		struct uni_screen *uniscr = get_vc_uniscr(vc);

		if (uniscr) {
		unsigned int s, d, rescue, clear;
		char32_t *save[nr];
		unsigned int i, j, k, sz, d, clear;

		s = clear = t;
		d = t + nr;
		rescue = b - nr;
		if (dir == SM_UP) {
		swap(s, d);
		swap(clear, rescue);
		sz = b - t;
		clear = b - nr;
		d = nr;
		if (dir == SM_DOWN) {
		clear = t;
		d = sz - nr;
		}
		for (i = 0; i < gcd(d, sz); i++) {
		char32_t *tmp = uniscr->lines[t + i];
		j = i;
		while (1) {
		k = j + d;
		if (k >= sz)
		k -= sz;
		if (k == i)
		break;
		uniscr->lines[t + j] = uniscr->lines[t + k];
		j = k;
		}
		uniscr->lines[t + j] = tmp;
		}
		memcpy(save, uniscr->lines + rescue, nr * sizeof(*save));
		memmove(uniscr->lines + d, uniscr->lines + s,
		(b - t - nr) * sizeof(*uniscr->lines));
		memcpy(uniscr->lines + clear, save, nr * sizeof(*save));
		vc_uniscr_clear_lines(vc, clear, nr);
		}
		}