linux-kernel - [PATCH] ata: sata_mv: Fix incorrect string length computation in mv_dump

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Message-Id: <1a35e114a3dcc33053ca7cca41cb06b8426d8c40.1693857262.git.christophe.jaillet@wanadoo.fr>
Date:   Mon,  4 Sep 2023 21:54:36 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Damien Le Moal <dlemoal@...nel.org>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        linux-ide@...r.kernel.org
Subject: [PATCH] ata: sata_mv: Fix incorrect string length computation in mv_dump_mem()

snprintf() returns the "number of characters which *would* be generated for
the given input", not the size *really* generated.

In order to avoid too large values for 'o' (and potential negative values
for "sizeof(linebuf) o") use scnprintf() instead of snprintf().

Note that given the "w < 4" in the for loop, the buffer can NOT
overflow, but using the *right* function is always better.

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
 drivers/ata/sata_mv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index d105db5c7d81..45e48d653c60 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -1255,8 +1255,8 @@ static void mv_dump_mem(struct device *dev, void __iomem *start, unsigned bytes)
 
 	for (b = 0; b < bytes; ) {
 		for (w = 0, o = 0; b < bytes && w < 4; w++) {
-			o += snprintf(linebuf + o, sizeof(linebuf) - o,
-				      "%08x ", readl(start + b));
+			o += scnprintf(linebuf + o, sizeof(linebuf) - o,
+				       "%08x ", readl(start + b));
 			b += sizeof(u32);
 		}
 		dev_dbg(dev, "%s: %p: %s\n",
-- 
2.34.1