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ppp, slip: Validate VJ compression slot parameters completely

Browse Source 
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: 郭永刚 <guoyonggang@360.cn>
References: http://article.gmane.org/gmane.comp.security.oss.general/17908
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ben Hutchings 2015-11-01 16:22:53 +00:00 committed by David S. Miller
parent 0baa57d8dc
commit 4ab42d78e3
4 changed files with 15 additions and 15 deletions
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10
drivers/isdn/i4l/isdn_ppp.c
View File

@ -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;

6
drivers/net/ppp/ppp_generic.c
View File

@ -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);

12
drivers/net/slip/slhc.c
View File

@ -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);
}

2
drivers/net/slip/slip.c
View File

@ -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);