Commit 8a085494 authored by Nicolas Pitre's avatar Nicolas Pitre Committed by Greg Kroah-Hartman
Browse files

vcsa: clamp header values when they don't fit 



The /dev/vcsa* devices have a fixed char-sized header that stores the
screen geometry and cursor location. Let's make sure it doesn't contain
random garbage when those values exceed 255. If ever it becomes necessary
to convey larger screen info to user space then a larger header in the
not-yet-implemented /dev/vcsua* devices should be considered.

Signed-off-by: default avatarNicolas Pitre <nico@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a5db4826

drivers/tty/vt/vc_screen.c

+3 −2
Original line number Diff line number Diff line
@@ -335,8 +335,9 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) 
			if (p < HEADER_SIZE) {

				size_t tmp_count;



				con_buf0[0] = (char)vc->vc_rows;

				con_buf0[1] = (char)vc->vc_cols;

				/* clamp header values if they don't fit */

				con_buf0[0] = min(vc->vc_rows, 0xFFu);

				con_buf0[1] = min(vc->vc_cols, 0xFFu);

				getconsxy(vc, con_buf0 + 2);



				con_buf_start += p;

drivers/tty/vt/vt.c

+3 −2
Original line number Diff line number Diff line
@@ -4607,8 +4607,9 @@ EXPORT_SYMBOL_GPL(screen_pos); 


void getconsxy(struct vc_data *vc, unsigned char *p)

{

	p[0] = vc->vc_x;

	p[1] = vc->vc_y;

	/* clamp values if they don't fit */

	p[0] = min(vc->vc_x, 0xFFu);

	p[1] = min(vc->vc_y, 0xFFu);

}



void putconsxy(struct vc_data *vc, unsigned char *p)

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