summaryrefslogtreecommitdiff
path: root/drivers/auxdisplay/img-ascii-lcd.c
diff options
context:
space:
mode:
authorGeert Uytterhoeven <geert@linux-m68k.org>2021-10-19 17:45:02 +0300
committerMiguel Ojeda <ojeda@kernel.org>2021-10-22 00:36:28 +0300
commitafcb5a811ff3ab3969f09666535eb6018a160358 (patch)
tree2a6d3c09e4975adfa8ab343171a500f5eb9ff40b /drivers/auxdisplay/img-ascii-lcd.c
parentae53c6963f5a3dc89dd04fa1372910e442fabc14 (diff)
downloadlinux-afcb5a811ff3ab3969f09666535eb6018a160358.tar.xz
auxdisplay: img-ascii-lcd: Fix lock-up when displaying empty string
While writing an empty string to a device attribute is a no-op, and thus does not need explicit safeguards, the user can still write a single newline to an attribute file: echo > .../message If that happens, img_ascii_lcd_display() trims the newline, yielding an empty string, and causing an infinite loop in img_ascii_lcd_scroll(). Fix this by adding a check for empty strings. Clear the display in case one is encountered. Fixes: 0cad855fbd083ee5 ("auxdisplay: img-ascii-lcd: driver for simple ASCII LCD displays") Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'drivers/auxdisplay/img-ascii-lcd.c')
-rw-r--r--drivers/auxdisplay/img-ascii-lcd.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/auxdisplay/img-ascii-lcd.c b/drivers/auxdisplay/img-ascii-lcd.c
index 1cce409ce5ca..e33ce0151cdf 100644
--- a/drivers/auxdisplay/img-ascii-lcd.c
+++ b/drivers/auxdisplay/img-ascii-lcd.c
@@ -280,6 +280,16 @@ static int img_ascii_lcd_display(struct img_ascii_lcd_ctx *ctx,
if (msg[count - 1] == '\n')
count--;
+ if (!count) {
+ /* clear the LCD */
+ devm_kfree(&ctx->pdev->dev, ctx->message);
+ ctx->message = NULL;
+ ctx->message_len = 0;
+ memset(ctx->curr, ' ', ctx->cfg->num_chars);
+ ctx->cfg->update(ctx);
+ return 0;
+ }
+
new_msg = devm_kmalloc(&ctx->pdev->dev, count + 1, GFP_KERNEL);
if (!new_msg)
return -ENOMEM;