[PATCH 06/12] usb: cdns2: Replace snprintf() with the safer scnprintf() variant
From: Lee Jones
Date: Wed Dec 13 2023 - 11:43:29 EST
There is a general misunderstanding amongst engineers that {v}snprintf()
returns the length of the data *actually* encoded into the destination
array. However, as per the C99 standard {v}snprintf() really returns
the length of the data that *would have been* written if there were
enough space for it. This misunderstanding has led to buffer-overruns
in the past. It's generally considered safer to use the {v}scnprintf()
variants in their place (or even sprintf() in simple cases). So let's
do that.
Link: https://lwn.net/Articles/69419/
Link: https://github.com/KSPP/linux/issues/105
Cc: Pawel Laszczak <pawell@xxxxxxxxxxx>
Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
---
drivers/usb/gadget/udc/cdns2/cdns2-debug.h | 138 ++++++++++-----------
1 file changed, 69 insertions(+), 69 deletions(-)
diff --git a/drivers/usb/gadget/udc/cdns2/cdns2-debug.h b/drivers/usb/gadget/udc/cdns2/cdns2-debug.h
index be9ae0d28a409..f5f330004190e 100644
--- a/drivers/usb/gadget/udc/cdns2/cdns2-debug.h
+++ b/drivers/usb/gadget/udc/cdns2/cdns2-debug.h
@@ -16,34 +16,34 @@ static inline const char *cdns2_decode_usb_irq(char *str, size_t size,
{
int ret;
- ret = snprintf(str, size, "usbirq: 0x%02x - ", usb_irq);
+ ret = scnprintf(str, size, "usbirq: 0x%02x - ", usb_irq);
if (usb_irq & USBIRQ_SOF)
- ret += snprintf(str + ret, size - ret, "SOF ");
+ ret += scnprintf(str + ret, size - ret, "SOF ");
if (usb_irq & USBIRQ_SUTOK)
- ret += snprintf(str + ret, size - ret, "SUTOK ");
+ ret += scnprintf(str + ret, size - ret, "SUTOK ");
if (usb_irq & USBIRQ_SUDAV)
- ret += snprintf(str + ret, size - ret, "SETUP ");
+ ret += scnprintf(str + ret, size - ret, "SETUP ");
if (usb_irq & USBIRQ_SUSPEND)
- ret += snprintf(str + ret, size - ret, "Suspend ");
+ ret += scnprintf(str + ret, size - ret, "Suspend ");
if (usb_irq & USBIRQ_URESET)
- ret += snprintf(str + ret, size - ret, "Reset ");
+ ret += scnprintf(str + ret, size - ret, "Reset ");
if (usb_irq & USBIRQ_HSPEED)
- ret += snprintf(str + ret, size - ret, "HS ");
+ ret += scnprintf(str + ret, size - ret, "HS ");
if (usb_irq & USBIRQ_LPM)
- ret += snprintf(str + ret, size - ret, "LPM ");
+ ret += scnprintf(str + ret, size - ret, "LPM ");
- ret += snprintf(str + ret, size - ret, ", EXT: 0x%02x - ", ext_irq);
+ ret += scnprintf(str + ret, size - ret, ", EXT: 0x%02x - ", ext_irq);
if (ext_irq & EXTIRQ_WAKEUP)
- ret += snprintf(str + ret, size - ret, "Wakeup ");
+ ret += scnprintf(str + ret, size - ret, "Wakeup ");
if (ext_irq & EXTIRQ_VBUSFAULT_FALL)
- ret += snprintf(str + ret, size - ret, "VBUS_FALL ");
+ ret += scnprintf(str + ret, size - ret, "VBUS_FALL ");
if (ext_irq & EXTIRQ_VBUSFAULT_RISE)
- ret += snprintf(str + ret, size - ret, "VBUS_RISE ");
+ ret += scnprintf(str + ret, size - ret, "VBUS_RISE ");
- if (ret >= size)
- pr_info("CDNS2: buffer overflowed.\n");
+ if (ret == size - 1)
+ pr_info("CDNS2: buffer may be truncated.\n");
return str;
}
@@ -54,28 +54,28 @@ static inline const char *cdns2_decode_dma_irq(char *str, size_t size,
{
int ret;
- ret = snprintf(str, size, "ISTS: %08x, %s: %08x ",
- ep_ists, ep_name, ep_sts);
+ ret = scnprintf(str, size, "ISTS: %08x, %s: %08x ",
+ ep_ists, ep_name, ep_sts);
if (ep_sts & DMA_EP_STS_IOC)
- ret += snprintf(str + ret, size - ret, "IOC ");
+ ret += scnprintf(str + ret, size - ret, "IOC ");
if (ep_sts & DMA_EP_STS_ISP)
- ret += snprintf(str + ret, size - ret, "ISP ");
+ ret += scnprintf(str + ret, size - ret, "ISP ");
if (ep_sts & DMA_EP_STS_DESCMIS)
- ret += snprintf(str + ret, size - ret, "DESCMIS ");
+ ret += scnprintf(str + ret, size - ret, "DESCMIS ");
if (ep_sts & DMA_EP_STS_TRBERR)
- ret += snprintf(str + ret, size - ret, "TRBERR ");
+ ret += scnprintf(str + ret, size - ret, "TRBERR ");
if (ep_sts & DMA_EP_STS_OUTSMM)
- ret += snprintf(str + ret, size - ret, "OUTSMM ");
+ ret += scnprintf(str + ret, size - ret, "OUTSMM ");
if (ep_sts & DMA_EP_STS_ISOERR)
- ret += snprintf(str + ret, size - ret, "ISOERR ");
+ ret += scnprintf(str + ret, size - ret, "ISOERR ");
if (ep_sts & DMA_EP_STS_DBUSY)
- ret += snprintf(str + ret, size - ret, "DBUSY ");
+ ret += scnprintf(str + ret, size - ret, "DBUSY ");
if (DMA_EP_STS_CCS(ep_sts))
- ret += snprintf(str + ret, size - ret, "CCS ");
+ ret += scnprintf(str + ret, size - ret, "CCS ");
- if (ret >= size)
- pr_info("CDNS2: buffer overflowed.\n");
+ if (ret == size - 1)
+ pr_info("CDNS2: buffer may be truncated.\n");
return str;
}
@@ -105,43 +105,43 @@ static inline const char *cdns2_raw_ring(struct cdns2_endpoint *pep,
int ret;
int i;
- ret = snprintf(str, size, "\n\t\tTR for %s:", pep->name);
+ ret = scnprintf(str, size, "\n\t\tTR for %s:", pep->name);
trb = &trbs[ring->dequeue];
dma = cdns2_trb_virt_to_dma(pep, trb);
- ret += snprintf(str + ret, size - ret,
- "\n\t\tRing deq index: %d, trb: V=%p, P=0x%pad\n",
- ring->dequeue, trb, &dma);
+ ret += scnprintf(str + ret, size - ret,
+ "\n\t\tRing deq index: %d, trb: V=%p, P=0x%pad\n",
+ ring->dequeue, trb, &dma);
trb = &trbs[ring->enqueue];
dma = cdns2_trb_virt_to_dma(pep, trb);
- ret += snprintf(str + ret, size - ret,
- "\t\tRing enq index: %d, trb: V=%p, P=0x%pad\n",
- ring->enqueue, trb, &dma);
+ ret += scnprintf(str + ret, size - ret,
+ "\t\tRing enq index: %d, trb: V=%p, P=0x%pad\n",
+ ring->enqueue, trb, &dma);
- ret += snprintf(str + ret, size - ret,
- "\t\tfree trbs: %d, CCS=%d, PCS=%d\n",
- ring->free_trbs, ring->ccs, ring->pcs);
+ ret += scnprintf(str + ret, size - ret,
+ "\t\tfree trbs: %d, CCS=%d, PCS=%d\n",
+ ring->free_trbs, ring->ccs, ring->pcs);
if (TRBS_PER_SEGMENT > 40) {
- ret += snprintf(str + ret, size - ret,
- "\t\tTransfer ring %d too big\n", TRBS_PER_SEGMENT);
+ ret += scnprintf(str + ret, size - ret,
+ "\t\tTransfer ring %d too big\n", TRBS_PER_SEGMENT);
return str;
}
dma = ring->dma;
for (i = 0; i < TRBS_PER_SEGMENT; ++i) {
trb = &trbs[i];
- ret += snprintf(str + ret, size - ret,
- "\t\t@%pad %08x %08x %08x\n", &dma,
- le32_to_cpu(trb->buffer),
- le32_to_cpu(trb->length),
- le32_to_cpu(trb->control));
+ ret += scnprintf(str + ret, size - ret,
+ "\t\t@%pad %08x %08x %08x\n", &dma,
+ le32_to_cpu(trb->buffer),
+ le32_to_cpu(trb->length),
+ le32_to_cpu(trb->control));
dma += sizeof(*trb);
}
- if (ret >= size)
- pr_info("CDNS2: buffer overflowed.\n");
+ if (ret == size - 1)
+ pr_info("CDNS2: buffer may be truncated.\n");
return str;
}
@@ -166,36 +166,36 @@ static inline const char *cdns2_decode_trb(char *str, size_t size, u32 flags,
switch (type) {
case TRB_LINK:
- ret = snprintf(str, size,
- "LINK %08x type '%s' flags %c:%c:%c%c:%c",
- buffer, cdns2_trb_type_string(type),
- flags & TRB_CYCLE ? 'C' : 'c',
- flags & TRB_TOGGLE ? 'T' : 't',
- flags & TRB_CHAIN ? 'C' : 'c',
- flags & TRB_CHAIN ? 'H' : 'h',
- flags & TRB_IOC ? 'I' : 'i');
+ ret = scnprintf(str, size,
+ "LINK %08x type '%s' flags %c:%c:%c%c:%c",
+ buffer, cdns2_trb_type_string(type),
+ flags & TRB_CYCLE ? 'C' : 'c',
+ flags & TRB_TOGGLE ? 'T' : 't',
+ flags & TRB_CHAIN ? 'C' : 'c',
+ flags & TRB_CHAIN ? 'H' : 'h',
+ flags & TRB_IOC ? 'I' : 'i');
break;
case TRB_NORMAL:
- ret = snprintf(str, size,
- "type: '%s', Buffer: %08x, length: %ld, burst len: %ld, "
- "flags %c:%c:%c%c:%c",
- cdns2_trb_type_string(type),
- buffer, TRB_LEN(length),
- TRB_FIELD_TO_BURST(length),
- flags & TRB_CYCLE ? 'C' : 'c',
- flags & TRB_ISP ? 'I' : 'i',
- flags & TRB_CHAIN ? 'C' : 'c',
- flags & TRB_CHAIN ? 'H' : 'h',
- flags & TRB_IOC ? 'I' : 'i');
+ ret = scnprintf(str, size,
+ "type: '%s', Buffer: %08x, length: %ld, burst len: %ld, "
+ "flags %c:%c:%c%c:%c",
+ cdns2_trb_type_string(type),
+ buffer, TRB_LEN(length),
+ TRB_FIELD_TO_BURST(length),
+ flags & TRB_CYCLE ? 'C' : 'c',
+ flags & TRB_ISP ? 'I' : 'i',
+ flags & TRB_CHAIN ? 'C' : 'c',
+ flags & TRB_CHAIN ? 'H' : 'h',
+ flags & TRB_IOC ? 'I' : 'i');
break;
default:
- ret = snprintf(str, size, "type '%s' -> raw %08x %08x %08x",
- cdns2_trb_type_string(type),
- buffer, length, flags);
+ ret = scnprintf(str, size, "type '%s' -> raw %08x %08x %08x",
+ cdns2_trb_type_string(type),
+ buffer, length, flags);
}
- if (ret >= size)
- pr_info("CDNS2: buffer overflowed.\n");
+ if (ret == size - 1)
+ pr_info("CDNS2: buffer may be truncated.\n");
return str;
}
--
2.43.0.472.g3155946c3a-goog