Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 3.15 069/109] net: ppp: fix creating PPP pass and active filters | Date | Sat, 26 Jul 2014 12:02:31 -0700 |
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3.15-stable review patch. If anyone has any objections, please let me know.
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From: Christoph Schulz <develop@kristov.de>
[ Upstream commit cc25eaae238ddd693aa5eaa73e565d8ff4915f6e ]
Commit 568f194e8bd16c353ad50f9ab95d98b20578a39d ("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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/isdn/i4l/isdn_ppp.c | 20 ++++++++++++++++---- drivers/net/ppp/ppp_generic.c | 22 ++++++++++++++++------ 2 files changed, 32 insertions(+), 10 deletions(-)
--- a/drivers/isdn/i4l/isdn_ppp.c +++ b/drivers/isdn/i4l/isdn_ppp.c @@ -644,9 +644,15 @@ isdn_ppp_ioctl(int min, struct file *fil 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; @@ -663,9 +669,15 @@ isdn_ppp_ioctl(int min, struct file *fil 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; --- a/drivers/net/ppp/ppp_generic.c +++ b/drivers/net/ppp/ppp_generic.c @@ -763,10 +763,15 @@ static long ppp_ioctl(struct file *file, }; 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); } @@ -784,10 +789,15 @@ static long ppp_ioctl(struct file *file, }; 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); }
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