On 3/5/19 12:50 PM, matthias.bgg@kernel.org wrote:

From: Matthias Brugger mbrugger@suse.com

Function term_read_reply tries to read from the serial console until the end_char was read. This can hang forever if we are, for some reason, not be able to read the full response (e.g. serial buffer too small, frame error). This patch moves the timeout detection into term_read_reply to assure we will make progress.

Fixes: 6bb591f704 ("efi_loader: query serial console size reliably") Signed-off-by: Matthias Brugger mbrugger@suse.com

---

Changes in v2:

• move timeout into term_get_char

lib/efi_loader/efi_console.c | 60 ++++++++++++++++++++---------------- 1 file changed, 33 insertions(+), 27 deletions(-)

diff --git a/lib/efi_loader/efi_console.c b/lib/efi_loader/efi_console.c index 66c33a551d..1133674faf 100644 --- a/lib/efi_loader/efi_console.c +++ b/lib/efi_loader/efi_console.c @@ -62,6 +62,21 @@ static struct simple_text_output_mode efi_con_mode = { .cursor_visible = 1, };

+static int term_get_char(char *c) +{

• u64 timeout;
• /* Wait up to 100 ms for a character */
• timeout = timer_get_us() + 100000;
• while (!tstc())

• if (timer_get_us() > timeout)
  

• 	return 1;
  

• *c = getc();
• return 0;

+}

/*

• Receive and parse a reply from the terminal.

@@ -75,31 +90,31 @@ static int term_read_reply(int *n, int num, char end_char) char c; int i = 0;

• c = getc();
• if (c != cESC)

• if (term_get_char(&c) || c != cESC) return -1;

• c = getc();
• if (c != '[')

• if (term_get_char(&c) || c != '[') return -1;

  n[0] = 0; while (1) {

• c = getc();
  

• if (c == ';') {
  

• 	i++;
  

• 	if (i >= num)
  

• if (!term_get_char(&c)) {
  

• 	if (c == ';') {
  

• 		i++;
  

• 		if (i >= num)
  

• 			return -1;
  

• 		n[i] = 0;
  

• 		continue;
  

• 	} else if (c == end_char) {
  

• 		break;
  

• 	} else if (c > '9' || c < '0') {
  	return -1;
  

• 	n[i] = 0;
  

• 	continue;
  

• } else if (c == end_char) {
  

• 	break;
  

• } else if (c > '9' || c < '0') {
  

• 	return -1;
  

• }
  

• 	}
  
  

• /* Read one more decimal position */
  

• n[i] *= 10;
  

• n[i] += c - '0';
  

• 	/* Read one more decimal position */
  

• 	n[i] *= 10;
  

• 	n[i] += c - '0';
  

• }
  

If no character is received we should throw an error:

} else { return -1;

Best regards

Heinrich

} if (i != num - 1) return -1; @@ -196,7 +211,6 @@ static int query_console_serial(int *rows, int *cols) { int ret = 0; int n[2];

• u64 timeout;

  /* Empty input buffer */ while (tstc())

@@ -216,14 +230,6 @@ static int query_console_serial(int *rows, int *cols) ESC "[999;999H" /* Move to bottom right corner */ ESC "[6n"); /* Query cursor position */

• /* Allow up to one second for a response */
• timeout = timer_get_us() + 1000000;
• while (!tstc())

• if (timer_get_us() > timeout) {
  

• 	ret = -1;
  

• 	goto out;
  

• }
  

• /* Read {rows,cols} */ if (term_read_reply(n, 2, 'R')) { ret = 1;