3.15-stable review patch. If anyone has any objections, please let me know.
------------------ From: Christoph Schulz <[email protected]> [ 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 <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
