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Commit 606f585e authored by Konstantin Sharlaimov's avatar Konstantin Sharlaimov Committed by David S. Miller
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[PPP_MPPE]: Fix "osize too small" check. 



Prevent mppe_decompress() from generating "osize too small" errors when
checking for output buffer size.  When receiving a packet of mru size the
output buffer for decrypted data is 1 byte too small since
mppe_decompress() tries to account for possible PFC, however later in code
it is assumed no PFC.

Adjusting the check prevented these errors from occurring.

Signed-off-by: default avatarKonstantin Sharlaimov <konstantin.sharlaimov@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9cadcd28

drivers/net/ppp_mppe.c

+5 −5
Original line number Diff line number Diff line
@@ -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.

	 * 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.

	 * 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.

	 */

	if (osize < isize - MPPE_OVHD - 1) {

	if (osize < isize - MPPE_OVHD - 2) {

		printk(KERN_DEBUG "mppe_decompress[%d]: osize too small! "

		       "(have: %d need: %d)\n", state->unit,

		       osize, isize - MPPE_OVHD - 1);

		       osize, isize - MPPE_OVHD - 2);

		return DECOMP_ERROR;

	}

	osize = isize - MPPE_OVHD - 2;	/* assume no PFC */