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Commit f3fce0c6 authored by Takashi Iwai's avatar Takashi Iwai Committed by Harshit Mogalapalli
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parport: Proper fix for array out-of-bounds access 



commit 02ac3a9ef3a18b58d8f3ea2b6e46de657bf6c4f9 upstream.

The recent fix for array out-of-bounds accesses replaced sprintf()
calls blindly with snprintf().  However, since snprintf() returns the
would-be-printed size, not the actually output size, the length
calculation can still go over the given limit.

Use scnprintf() instead of snprintf(), which returns the actually
output letters, for addressing the potential out-of-bounds access
properly.

Fixes: ab11dac93d2d ("dev/parport: fix the array out-of-bounds risk")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20240920103318.19271-1-tiwai@suse.de


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 8aadef73)
Signed-off-by: default avatarVegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: default avatarHarshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
parent 1128e72f

drivers/parport/procfs.c

+11 −11
Original line number Diff line number Diff line
@@ -51,12 +51,12 @@ static int do_active_device(struct ctl_table *table, int write, 
	

	for (dev = port->devices; dev ; dev = dev->next) {

		if(dev == port->cad) {

			len += snprintf(buffer, sizeof(buffer), "%s\n", dev->name);

			len += scnprintf(buffer, sizeof(buffer), "%s\n", dev->name);

		}

	}



	if(!len) {

		len += snprintf(buffer, sizeof(buffer), "%s\n", "none");

		len += scnprintf(buffer, sizeof(buffer), "%s\n", "none");

	}



	if (len > *lenp)
@@ -87,19 +87,19 @@ static int do_autoprobe(struct ctl_table *table, int write, 
	}

	

	if ((str = info->class_name) != NULL)

		len += snprintf (buffer + len, sizeof(buffer) - len, "CLASS:%s;\n", str);

		len += scnprintf (buffer + len, sizeof(buffer) - len, "CLASS:%s;\n", str);



	if ((str = info->model) != NULL)

		len += snprintf (buffer + len, sizeof(buffer) - len, "MODEL:%s;\n", str);

		len += scnprintf (buffer + len, sizeof(buffer) - len, "MODEL:%s;\n", str);



	if ((str = info->mfr) != NULL)

		len += snprintf (buffer + len, sizeof(buffer) - len, "MANUFACTURER:%s;\n", str);

		len += scnprintf (buffer + len, sizeof(buffer) - len, "MANUFACTURER:%s;\n", str);



	if ((str = info->description) != NULL)

		len += snprintf (buffer + len, sizeof(buffer) - len, "DESCRIPTION:%s;\n", str);

		len += scnprintf (buffer + len, sizeof(buffer) - len, "DESCRIPTION:%s;\n", str);



	if ((str = info->cmdset) != NULL)

		len += snprintf (buffer + len, sizeof(buffer) - len, "COMMAND SET:%s;\n", str);

		len += scnprintf (buffer + len, sizeof(buffer) - len, "COMMAND SET:%s;\n", str);



	if (len > *lenp)

		len = *lenp;
@@ -128,7 +128,7 @@ static int do_hardware_base_addr(struct ctl_table *table, int write, 
	if (write) /* permissions prevent this anyway */

		return -EACCES;



	len += snprintf (buffer, sizeof(buffer), "%lu\t%lu\n", port->base, port->base_hi);

	len += scnprintf (buffer, sizeof(buffer), "%lu\t%lu\n", port->base, port->base_hi);



	if (len > *lenp)

		len = *lenp;
@@ -156,7 +156,7 @@ static int do_hardware_irq(struct ctl_table *table, int write, 
	if (write) /* permissions prevent this anyway */

		return -EACCES;



	len += snprintf (buffer, sizeof(buffer), "%d\n", port->irq);

	len += scnprintf (buffer, sizeof(buffer), "%d\n", port->irq);



	if (len > *lenp)

		len = *lenp;
@@ -184,7 +184,7 @@ static int do_hardware_dma(struct ctl_table *table, int write, 
	if (write) /* permissions prevent this anyway */

		return -EACCES;



	len += snprintf (buffer, sizeof(buffer), "%d\n", port->dma);

	len += scnprintf (buffer, sizeof(buffer), "%d\n", port->dma);



	if (len > *lenp)

		len = *lenp;
@@ -216,7 +216,7 @@ static int do_hardware_modes(struct ctl_table *table, int write, 
#define printmode(x)							\

do {									\

	if (port->modes & PARPORT_MODE_##x)				\

		len += snprintf(buffer + len, sizeof(buffer) - len, "%s%s", f++ ? "," : "", #x); \

		len += scnprintf(buffer + len, sizeof(buffer) - len, "%s%s", f++ ? "," : "", #x); \

} while (0)

		int f = 0;

		printmode(PCSPP);