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net: ppp: fix creating PPP pass and active filters

Browse source 
Commit 568f194e8b ("net: ppp: use
sk_unattached_filter api") inadvertently changed the logic when setting
PPP pass and active filters. This applies to both the generic PPP subsystem
implemented by drivers/net/ppp/ppp_generic.c and the ISDN PPP subsystem
implemented by drivers/isdn/i4l/isdn_ppp.c. The original code in ppp_ioctl()
(or isdn_ppp_ioctl(), resp.) handling PPPIOCSPASS and PPPIOCSACTIVE allowed to
remove a pass/active filter previously set by using a filter of length zero.
However, with the new code this is not possible anymore as this case is not
explicitly checked for, which leads to passing NULL as a filter to
sk_unattached_filter_create(). This results in returning EINVAL to the caller.

Additionally, the variables ppp->pass_filter and ppp->active_filter (or
is->pass_filter and is->active_filter, resp.) are not reset to NULL, although
the filters they point to may have been destroyed by
sk_unattached_filter_destroy(), so in this EINVAL case dangling pointers are
left behind (provided the pointers were previously non-NULL).

This patch corrects both problems by checking whether the filter passed is
empty or non-empty, and prevents sk_unattached_filter_create() from being
called in the first case. Moreover, the pointers are always reset to NULL
as soon as sk_unattached_filter_destroy() returns.

Signed-off-by: Christoph Schulz <develop@kristov.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Christoph Schulz 2014-07-16 22:10:29 +02:00 committed by David S. Miller
parent 858e6c3210
commit cc25eaae23
2 changed files with 32 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

20
drivers/isdn/i4l/isdn_ppp.c
View file

@ -638,9 +638,15 @@ isdn_ppp_ioctl(int min, struct file *file, unsigned int cmd, unsigned long arg)
fprog.len = len;
fprog.filter = code;
if (is->pass_filter)
if (is->pass_filter) {
sk_unattached_filter_destroy(is->pass_filter);
err = sk_unattached_filter_create(&is->pass_filter, &fprog);
is->pass_filter = NULL;
}
if (fprog.filter != NULL)
err = sk_unattached_filter_create(&is->pass_filter,
&fprog);
else
err = 0;
kfree(code);
return err;
@ -657,9 +663,15 @@ isdn_ppp_ioctl(int min, struct file *file, unsigned int cmd, unsigned long arg)
fprog.len = len;
fprog.filter = code;
if (is->active_filter)
if (is->active_filter) {
sk_unattached_filter_destroy(is->active_filter);
err = sk_unattached_filter_create(&is->active_filter, &fprog);
is->active_filter = NULL;
}
if (fprog.filter != NULL)
err = sk_unattached_filter_create(&is->active_filter,
&fprog);
else
err = 0;
kfree(code);
return err;

22
drivers/net/ppp/ppp_generic.c
View file

@ -757,10 +757,15 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
};
ppp_lock(ppp);
if (ppp->pass_filter)
if (ppp->pass_filter) {
sk_unattached_filter_destroy(ppp->pass_filter);
err = sk_unattached_filter_create(&ppp->pass_filter,
&fprog);
ppp->pass_filter = NULL;
}
if (fprog.filter != NULL)
err = sk_unattached_filter_create(&ppp->pass_filter,
&fprog);
else
err = 0;
kfree(code);
ppp_unlock(ppp);
}
@ -778,10 +783,15 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
};
ppp_lock(ppp);
if (ppp->active_filter)
if (ppp->active_filter) {
sk_unattached_filter_destroy(ppp->active_filter);
err = sk_unattached_filter_create(&ppp->active_filter,
&fprog);
ppp->active_filter = NULL;
}
if (fprog.filter != NULL)
err = sk_unattached_filter_create(&ppp->active_filter,
&fprog);
else
err = 0;
kfree(code);
ppp_unlock(ppp);
}