linux-kernel - [PATCH v2 1/3] staging/fbtft: Remove all strcpy() uses

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Message-Id: <20210724151411.9531-2-len.baker@gmx.com>
Date:   Sat, 24 Jul 2021 17:14:09 +0200
From:   Len Baker <len.baker@....com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Len Baker <len.baker@....com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Phil Reid <preid@...ctromag.com.au>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/3] staging/fbtft: Remove all strcpy() uses

strcpy() performs no bounds checking on the destination buffer. This
could result in linear overflows beyond the end of the buffer, leading
to all kinds of misbehaviors. The safe replacement is strscpy() but in
this case it is simpler to use the "%*ph" format specifier.

Signed-off-by: Len Baker <len.baker@....com>
---
 drivers/staging/fbtft/fbtft-core.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
index 3723269890d5..be20da3c4a5c 100644
--- a/drivers/staging/fbtft/fbtft-core.c
+++ b/drivers/staging/fbtft/fbtft-core.c
@@ -992,8 +992,6 @@ static int fbtft_init_display_from_property(struct fbtft_par *par)
 int fbtft_init_display(struct fbtft_par *par)
 {
 	int buf[64];
-	char msg[128];
-	char str[16];
 	int i = 0;
 	int j;

@@ -1036,17 +1034,14 @@ int fbtft_init_display(struct fbtft_par *par)
 		switch (par->init_sequence[i]) {
 		case -1:
 			i++;
+
 			/* make debug message */
-			strcpy(msg, "");
-			j = i + 1;
-			while (par->init_sequence[j] >= 0) {
-				sprintf(str, "0x%02X ", par->init_sequence[j]);
-				strcat(msg, str);
-				j++;
-			}
+			for (j = i + 1; par->init_sequence[j] >= 0; j++);
+
 			fbtft_par_dbg(DEBUG_INIT_DISPLAY, par,
-				      "init: write(0x%02X) %s\n",
-				      par->init_sequence[i], msg);
+				      "init: write(0x%02X) %*ph\n",
+				      par->init_sequence[i], j - i - 1,
+				      &par->init_sequence[i + 1]);

 			/* Write */
 			j = 0;
--
2.25.1