[PATCH net-next v5 4/8] net: pktgen: fix mpls maximum labels list parsing

[Peter Seiderer]

Fix mpls maximum labels list parsing up to MAX_MPLS_LABELS/16 entries
(instead of up to MAX_MPLS_LABELS - 1).

Addresses the following:

        $ echo "mpls 
00000f00,00000f01,00000f02,00000f03,00000f04,00000f05,00000f06,00000f07,00000f08,00000f09,00000f0a,00000f0b,00000f0c,00000f0d,00000f0e,00000f0f"
 > /proc/net/pktgen/lo\@0
        -bash: echo: write error: Argument list too long

Signed-off-by: Peter Seiderer <ps.rep...@gmx.net>
---
Changes v4 -> v5
  - split up patchset into part i/ii (suggested by Simon Horman)
  - change patch description ('Fixes:' -> 'Addresses the following:',
    suggested by Simon Horman)

Changes v3 -> v4
  - new patch (factored out of patch 'net: pktgen: fix access outside of user
    given buffer in pktgen_if_write()')
---
 net/core/pktgen.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 436076a2ccb7..9b63feb8a33e 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -911,6 +911,10 @@ static ssize_t get_labels(const char __user *buffer, 
struct pktgen_dev *pkt_dev)
        pkt_dev->nr_labels = 0;
        do {
                __u32 tmp;
+
+               if (n >= MAX_MPLS_LABELS)
+                       return -E2BIG;
+
                len = hex32_arg(&buffer[i], HEX_8_DIGITS, &tmp);
                if (len <= 0)
                        return len;
@@ -922,8 +926,6 @@ static ssize_t get_labels(const char __user *buffer, struct 
pktgen_dev *pkt_dev)
                        return -EFAULT;
                i++;
                n++;
-               if (n >= MAX_MPLS_LABELS)
-                       return -E2BIG;
        } while (c == ',');
 
        pkt_dev->nr_labels = n;
-- 
2.48.1