linux-kernel - Re: [RESEND] edac: replace sprintf() by scnprintf()

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Message-ID: <d95595021eb8da542960fff9b40dc7c308661c9e.camel@perches.com>
Date:   Sat, 10 Jul 2021 09:58:46 -0700
From:   Joe Perches <joe@...ches.com>
To:     Salah Triki <salah.triki@...il.com>, bp@...en8.de,
        mchehab@...nel.org, tony.luck@...el.com, james.morse@....com,
        rric@...nel.org
Cc:     linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND] edac: replace sprintf() by scnprintf()

On Sat, 2021-07-10 at 17:35 +0100, Salah Triki wrote:
> Replace sprintf() by scnprintf() in order to avoid buffer overflows.

While of course safe, this is not strictly necessary as the
maximum length of any edac_layer_name is 8 bytes.

drivers/edac/edac_mc.c:const char *edac_layer_name[] = {
drivers/edac/edac_mc.c- [EDAC_MC_LAYER_BRANCH] = "branch",
drivers/edac/edac_mc.c- [EDAC_MC_LAYER_CHANNEL] = "channel",
drivers/edac/edac_mc.c- [EDAC_MC_LAYER_SLOT] = "slot",
drivers/edac/edac_mc.c- [EDAC_MC_LAYER_CHIP_SELECT] = "csrow",
drivers/edac/edac_mc.c- [EDAC_MC_LAYER_ALL_MEM] = "memory",
drivers/edac/edac_mc.c-};

And name is:

		char name[80];

I suppose name[80] could be changed to name[32] or so
at the same time to reduce stack usage.

Maybe name should be moved into the loop too.

---
 drivers/edac/debugfs.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/edac/debugfs.c b/drivers/edac/debugfs.c
index 4804332d99465..a41071f2ad428 100644
--- a/drivers/edac/debugfs.c
+++ b/drivers/edac/debugfs.c
@@ -55,14 +55,15 @@ void edac_debugfs_exit(void)
 void edac_create_debugfs_nodes(struct mem_ctl_info *mci)
 {
 	struct dentry *parent;
-	char name[80];
 	int i;
 
 	parent = debugfs_create_dir(mci->dev.kobj.name, edac_debugfs);
 
 	for (i = 0; i < mci->n_layers; i++) {
-		sprintf(name, "fake_inject_%s",
-			     edac_layer_name[mci->layers[i].type]);
+		char name[32];
+
+		scnprintf(name, sizeof(name), "fake_inject_%s",
+			  edac_layer_name[mci->layers[i].type]);
 		debugfs_create_u8(name, S_IRUGO | S_IWUSR, parent,
 				  &mci->fake_inject_layer[i]);
 	}