isdn/gigaset: limit raw CAPI message dump length

In dump_rawmsg, the length field from a received data package was
used unscrutinized, allowing an attacker to control the size of the
allocated buffer and the number of times the output loop iterates.
Fix by limiting to a reasonable value.

Spotted with Coverity.

Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/isdn/gigaset/capi.c b/drivers/isdn/gigaset/capi.c
index 044392cba262..47e2a913a6ef 100644
--- a/drivers/isdn/gigaset/capi.c
+++ b/drivers/isdn/gigaset/capi.c
@@ -250,6 +250,8 @@ static inline void dump_rawmsg(enum debuglevel level, const char *tag,
         l -= 12;
         if (l <= 0)
                 return;
+        if (l > 64)
+                l = 64; /* arbitrary limit */
         dbgline = kmalloc(3 * l, GFP_ATOMIC);
         if (!dbgline)
                 return;