Hi Gleb and Hiren, > On Oct 4, 2016, at 1:59 PM, Hiren Panchasara <hi...@freebsd.org> wrote: > > + Lohith > > On 10/04/16 at 01:53P, Gleb Smirnoff wrote: >> Hiren, >> >> On Mon, Sep 26, 2016 at 10:13:58AM +0000, Hiren Panchasara wrote: >> H> Author: hiren >> H> Date: Mon Sep 26 10:13:58 2016 >> H> New Revision: 306337 >> H> URL: https://svnweb.freebsd.org/changeset/base/306337 >> H> >> H> Log: >> H> In sendit(), if mp->msg_control is present, then in sockargs() we are >> allocating >> H> mbuf to store mp->msg_control. Later in kern_sendit(), call to >> getsock_cap(), >> H> will check validity of file pointer passed, if this fails EBADF is >> returned but >> H> mbuf allocated in sockargs() is not freed. Fix this possible leak. >> H> >> H> Submitted by: Lohith Bellad <lohith.bel...@me.com> >> H> Reviewed by: adrian >> H> MFC after: 3 weeks >> H> Differential Revision: https://reviews.freebsd.org/D7910 >> >> The commit appeared to be incorrect, but a problem exists. I'd like to look >> at it. >> Is there any reproduce recipe for the leak or bug filed? >>
I figured out a way to prevent this leak. I completed running stress test on the image built with this patch and it looks fine. I will send out for review once I reach my FreeBSD system tonight. This is regarding the following commit, which led to kernel panic!!! https://svnweb.freebsd.org/base?view=revision&revision=306337 <https://svnweb.freebsd.org/base?view=revision&revision=306337> Discussion thread regarding the kernel panic, https://lists.freebsd.org/pipermail/svn-src-head/2016-September/092110.html <https://lists.freebsd.org/pipermail/svn-src-head/2016-September/092110.html> Thanks a lot for the input and sorry for the trouble created. Modified diff: Since its not possible to check and free the control mbuf correclty in sendit() routine. We can clear the control mbuf in kern_sendit() routine after checking correctly. Here is the diff, Index: sys/kern/uipc_syscalls.c =================================================================== --- sys/kern/uipc_syscalls.c (revision 305955) +++ sys/kern/uipc_syscalls.c (working copy) @@ -809,6 +809,9 @@ } if (error == 0) td->td_retval[0] = len - auio.uio_resid; + + /* call to sosend would have cleared control */ + control = NULL; #ifdef KTRACE if (ktruio != NULL) { ktruio->uio_resid = td->td_retval[0]; @@ -816,6 +819,8 @@ } #endif bad: + if (control != NULL) + m_freem(control); fdrop(fp, td); return (error); } Since, we know for sure sosend() routine will consume the control mbuf if its present else it will clear the mbuf. So, making control = NULL, after the call to sosend() will prevent double freeing of control mbuf. If there are any errors before call to sosend() in kern_sendit(), for example EBADF (Bad File Descriptor) then we will fall to "bad:" and if control != NULL, we will clear the mbuf. This way mbuf leak for EBADF is also prevented. Cheers, Lohith _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
