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>

diff --git a/drivers/isdn/gigaset/capi.c b/drivers/isdn/gigaset/capi.c
index 044392c..47e2a91 100644 (file)
--- 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;