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Message-ID: <1444845210.31451.23.camel@decadent.org.uk>
Date: Wed, 14 Oct 2015 18:53:30 +0100
From: Ben Hutchings <ben@...adent.org.uk>
To: David Miller <davem@...emloft.net>
Cc: Karsten Keil <isdn@...ux-pingi.de>, linux-ppp@...r.kernel.org,
netdev <netdev@...r.kernel.org>,
郭永刚 <guoyonggang@....cn>
Subject: [PATCH 2/2] 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: 郭永刚 <guoyonggang@....cn>
References: http://article.gmane.org/gmane.comp.security.oss.general/17908
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
drivers/isdn/i4l/isdn_ppp.c | 10 ++++------
drivers/net/ppp/ppp_generic.c | 6 ++----
drivers/net/slip/slhc.c | 12 ++++++++----
drivers/net/slip/slip.c | 2 +-
4 files changed, 15 insertions(+), 15 deletions(-)
diff --git a/drivers/isdn/i4l/isdn_ppp.c b/drivers/isdn/i4l/isdn_ppp.c
index 86f9abe..9c1e8ad 100644
--- a/drivers/isdn/i4l/isdn_ppp.c
+++ b/drivers/isdn/i4l/isdn_ppp.c
@@ -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;
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index ed00446..9a863c6 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -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);
diff --git a/drivers/net/slip/slhc.c b/drivers/net/slip/slhc.c
index 079f7ad..27ed252 100644
--- a/drivers/net/slip/slhc.c
+++ b/drivers/net/slip/slhc.c
@@ -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);
}
diff --git a/drivers/net/slip/slip.c b/drivers/net/slip/slip.c
index 05387b1..a17d86a 100644
--- a/drivers/net/slip/slip.c
+++ b/drivers/net/slip/slip.c
@@ -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);
--
Ben Hutchings
[W]e found...that it wasn't as easy to get programs right as we had thought.
... I realized that a large part of my life from then on was going to be spent
in finding mistakes in my own programs. - Maurice Wilkes, 1949
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