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Commit 555d5b70 authored by Guillaume Nault's avatar Guillaume Nault Committed by David S. Miller
Browse files

ppp: clarify parsing of user supplied data in ppp_set_compress() 



* Split big conditional statement.
  * Check (data.length <= CCP_MAX_OPTION_LENGTH) only once.
  * Don't read ccp_option[1] if not initialised.

Reading uninitialised ccp_option[1] was harmless, because this could
only happen when data.length was 0 or 1. So even then, we couldn't pass
the (ccp_option[1] < 2 || ccp_option[1] > data.length) test anyway.

Signed-off-by: default avatarGuillaume Nault <g.nault@alphalink.fr>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4fee7dab

drivers/net/ppp/ppp_generic.c

+7 −5
Original line number Diff line number Diff line
@@ -2429,13 +2429,15 @@ ppp_set_compress(struct ppp *ppp, unsigned long arg) 
	unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];



	err = -EFAULT;

	if (copy_from_user(&data, (void __user *) arg, sizeof(data)) ||

	    (data.length <= CCP_MAX_OPTION_LENGTH &&

	     copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))

	if (copy_from_user(&data, (void __user *) arg, sizeof(data)))

		goto out;

	if (data.length > CCP_MAX_OPTION_LENGTH)

		goto out;

	if (copy_from_user(ccp_option, (void __user *) data.ptr, data.length))

		goto out;



	err = -EINVAL;

	if (data.length > CCP_MAX_OPTION_LENGTH ||

	    ccp_option[1] < 2 || ccp_option[1] > data.length)

	if (data.length < 2 || ccp_option[1] < 2 || ccp_option[1] > data.length)

		goto out;



	cp = try_then_request_module(