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@xxxxxx> References: http://article.gmane.org/gmane.comp.security.oss.general/17908 Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- Re-sent using mutt since Evolution 3.18 mangles patches. Ben. 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);
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