Commit 4ab42d78 authored by Ben Hutchings's avatar Ben Hutchings Committed by David S. Miller
Browse files

ppp, slip: Validate VJ compression slot parameters completely 



Currently slhc_init() treats out-of-range values of rslots and tslots
as equivalent to 0, except that if tslots is too large it will
dereference a null pointer (CVE-2015-7799).

Add a range-check at the top of the function and make it return an
ERR_PTR() on error instead of NULL.  Change the callers accordingly.

Compile-tested only.

Reported-by: default avatar郭永刚 <guoyonggang@360.cn>
References: http://article.gmane.org/gmane.comp.security.oss.general/17908


Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0baa57d8

drivers/isdn/i4l/isdn_ppp.c

+4 −6
Original line number Diff line number Diff line
@@ -322,9 +322,9 @@ isdn_ppp_open(int min, struct file *file) 
	 * VJ header compression init

	 */

	is->slcomp = slhc_init(16, 16);	/* not necessary for 2. link in bundle */

	if (!is->slcomp) {

	if (IS_ERR(is->slcomp)) {

		isdn_ppp_ccp_reset_free(is);

		return -ENOMEM;

		return PTR_ERR(is->slcomp);

	}

#endif

#ifdef CONFIG_IPPP_FILTER
@@ -573,10 +573,8 @@ isdn_ppp_ioctl(int min, struct file *file, unsigned int cmd, unsigned long arg) 
			is->maxcid = val;

#ifdef CONFIG_ISDN_PPP_VJ

			sltmp = slhc_init(16, val);

			if (!sltmp) {

				printk(KERN_ERR "ippp, can't realloc slhc struct\n");

				return -ENOMEM;

			}

			if (IS_ERR(sltmp))

				return PTR_ERR(sltmp);

			if (is->slcomp)

				slhc_free(is->slcomp);

			is->slcomp = sltmp;

drivers/net/ppp/ppp_generic.c

+2 −4
Original line number Diff line number Diff line
@@ -721,10 +721,8 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 
			val &= 0xffff;

		}

		vj = slhc_init(val2+1, val+1);

		if (!vj) {

			netdev_err(ppp->dev,

				   "PPP: no memory (VJ compressor)\n");

			err = -ENOMEM;

		if (IS_ERR(vj)) {

			err = PTR_ERR(vj);

			break;

		}

		ppp_lock(ppp);

drivers/net/slip/slhc.c

+8 −4
Original line number Diff line number Diff line
@@ -84,8 +84,9 @@ static long decode(unsigned char **cpp); 
static unsigned char * put16(unsigned char *cp, unsigned short x);

static unsigned short pull16(unsigned char **cpp);



/* Initialize compression data structure

/* Allocate compression data structure

 *	slots must be in range 0 to 255 (zero meaning no compression)

 * Returns pointer to structure or ERR_PTR() on error.

 */

struct slcompress *

slhc_init(int rslots, int tslots)
@@ -94,11 +95,14 @@ slhc_init(int rslots, int tslots) 
	register struct cstate *ts;

	struct slcompress *comp;



	if (rslots < 0 || rslots > 255 || tslots < 0 || tslots > 255)

		return ERR_PTR(-EINVAL);



	comp = kzalloc(sizeof(struct slcompress), GFP_KERNEL);

	if (! comp)

		goto out_fail;



	if ( rslots > 0  &&  rslots < 256 ) {

	if (rslots > 0) {

		size_t rsize = rslots * sizeof(struct cstate);

		comp->rstate = kzalloc(rsize, GFP_KERNEL);

		if (! comp->rstate)
@@ -106,7 +110,7 @@ slhc_init(int rslots, int tslots) 
		comp->rslot_limit = rslots - 1;

	}



	if ( tslots > 0  &&  tslots < 256 ) {

	if (tslots > 0) {

		size_t tsize = tslots * sizeof(struct cstate);

		comp->tstate = kzalloc(tsize, GFP_KERNEL);

		if (! comp->tstate)
@@ -141,7 +145,7 @@ out_free2: 
out_free:

	kfree(comp);

out_fail:

	return NULL;

	return ERR_PTR(-ENOMEM);

}

drivers/net/slip/slip.c

+1 −1
Original line number Diff line number Diff line
@@ -164,7 +164,7 @@ static int sl_alloc_bufs(struct slip *sl, int mtu) 
	if (cbuff == NULL)

		goto err_exit;

	slcomp = slhc_init(16, 16);

	if (slcomp == NULL)

	if (IS_ERR(slcomp))

		goto err_exit;

#endif

	spin_lock_bh(&sl->lock);

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