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parport: Proper fix for array out-of-bounds access

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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: ab11dac93d ("dev/parport: fix the array out-of-bounds risk")
Cc: stable@vger.kernel.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20240920103318.19271-1-tiwai@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Takashi Iwai 2024-09-20 12:32:19 +02:00 committed by Greg Kroah-Hartman
parent 01a2d6eeb6
commit 2a8b26a09c
1 changed files with 11 additions and 11 deletions
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22
drivers/parport/procfs.c
View file

@ -51,12 +51,12 @@ static int do_active_device(const 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(const 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(const 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;
@ -155,7 +155,7 @@ static int do_hardware_irq(const 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;
@ -182,7 +182,7 @@ static int do_hardware_dma(const 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;
@ -213,7 +213,7 @@ static int do_hardware_modes(const 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);