[PPP]: Revert 606f585e363527da9feaed79465132c0c661fd9e

This can cause packet buffer overflows in certain cases,
the real bug will be fixed differently in a followon
changeset.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ppp_mppe.c b/drivers/net/ppp_mppe.c
index 5ae80bbe2edca0dcd698960553ed493e0a6dd4d9..d5bdd25746591a8b0bb47b2dca226b3fbca34fcf 100644 (file)
--- a/drivers/net/ppp_mppe.c
+++ b/drivers/net/ppp_mppe.c
@@ -493,14 +493,14 @@ mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf,
 
        /*
         * Make sure we have enough room to decrypt the packet.
-        * To account for possible PFC we should only subtract 1
-        * byte whereas in mppe_compress() we added 2 bytes (+MPPE_OVHD);
-        * However, we assume no PFC, thus subtracting 2 bytes.
+        * Note that for our test we only subtract 1 byte whereas in
+        * mppe_compress() we added 2 bytes (+MPPE_OVHD);
+        * this is to account for possible PFC.
         */
-       if (osize < isize - MPPE_OVHD - 2) {
+       if (osize < isize - MPPE_OVHD - 1) {
                printk(KERN_DEBUG "mppe_decompress[%d]: osize too small! "
                       "(have: %d need: %d)\n", state->unit,
-                      osize, isize - MPPE_OVHD - 2);
+                      osize, isize - MPPE_OVHD - 1);
                return DECOMP_ERROR;
        }
        osize = isize - MPPE_OVHD - 2;  /* assume no PFC */